From 68fc602db667a3134718c9c1b957dccfe8f1f2af Mon Sep 17 00:00:00 2001
From: Fedor <fedor@mail.ru>
Date: Thu, 16 Jul 2020 03:44:38 +0300
Subject: [PATCH] Re-architecture DOM script loading.

---
 dom/base/ImportManager.cpp                    |   8 +-
 dom/base/ImportManager.h                      |   8 +-
 dom/base/Location.cpp                         |   2 +-
 dom/base/moz.build                            |   7 -
 dom/base/nsContentPermissionHelper.cpp        |   3 +-
 dom/base/nsContentSink.cpp                    |   2 +-
 dom/base/nsContentSink.h                      |   7 +-
 dom/base/nsDocument.cpp                       |   4 +-
 dom/base/nsDocument.h                         |   6 +-
 dom/base/nsFrameMessageManager.cpp            |   8 +-
 dom/base/nsGlobalWindow.cpp                   |   2 +-
 dom/base/nsIDocument.h                        |   4 +-
 dom/base/nsInProcessTabChildGlobal.cpp        |   2 +-
 dom/base/nsJSEnvironment.cpp                  |   2 +-
 dom/base/nsPlainTextSerializer.h              |   1 +
 dom/console/Console.cpp                       |   2 +-
 dom/events/DOMEventTargetHelper.cpp           |   2 +-
 dom/html/HTMLScriptElement.cpp                |   2 +-
 dom/html/HTMLScriptElement.h                  |   7 +-
 dom/html/nsGenericHTMLElement.cpp             |   2 +-
 dom/html/nsHTMLContentSink.cpp                |   2 +-
 dom/messagechannel/MessagePort.cpp            |   2 +-
 dom/moz.build                                 |   1 +
 dom/script/ModuleLoadRequest.cpp              | 102 ++
 dom/script/ModuleLoadRequest.h                |  81 ++
 dom/script/ModuleScript.cpp                   | 100 ++
 dom/script/ModuleScript.h                     |  67 ++
 .../ScriptElement.cpp}                        |  60 +-
 .../ScriptElement.h}                          |  18 +-
 dom/script/ScriptLoadHandler.cpp              | 216 +++++
 dom/script/ScriptLoadHandler.h                |  76 ++
 .../ScriptLoader.cpp}                         | 876 ++++--------------
 .../ScriptLoader.h}                           | 227 ++---
 dom/{base => script}/ScriptSettings.cpp       |   0
 dom/{base => script}/ScriptSettings.h         |   0
 dom/script/moz.build                          |  36 +
 dom/{base => script}/nsIScriptElement.h       |   0
 .../nsIScriptLoaderObserver.idl               |   0
 dom/svg/SVGScriptElement.cpp                  |   4 +-
 dom/svg/SVGScriptElement.h                    |   6 +-
 dom/workers/ScriptLoader.cpp                  |  20 +-
 dom/workers/ServiceWorkerManager.cpp          |   2 +-
 dom/workers/ServiceWorkerScriptCache.cpp      |  14 +-
 dom/worklet/Worklet.cpp                       |   8 +-
 dom/xml/nsXMLContentSink.cpp                  |   2 +-
 dom/xml/nsXMLFragmentContentSink.cpp          |   2 +-
 dom/xslt/xslt/txMozillaXMLOutput.cpp          |   8 +-
 dom/xul/XULDocument.cpp                       |   8 +-
 dom/xul/XULDocument.h                         |   2 +-
 dom/xul/nsXULContentSink.cpp                  |   2 +-
 js/xpconnect/loader/mozJSSubScriptLoader.cpp  |  12 +-
 js/xpconnect/src/XPCJSContext.cpp             |   6 +-
 parser/html/nsHtml5DocumentBuilder.cpp        |   2 +-
 parser/html/nsHtml5OplessBuilder.cpp          |   2 +-
 parser/html/nsHtml5TreeOpExecutor.cpp         |   2 +-
 parser/html/nsParserUtils.cpp                 |   4 +-
 parser/htmlparser/nsParser.cpp                |   2 +-
 57 files changed, 1105 insertions(+), 948 deletions(-)
 create mode 100644 dom/script/ModuleLoadRequest.cpp
 create mode 100644 dom/script/ModuleLoadRequest.h
 create mode 100644 dom/script/ModuleScript.cpp
 create mode 100644 dom/script/ModuleScript.h
 rename dom/{base/nsScriptElement.cpp => script/ScriptElement.cpp} (64%)
 rename dom/{base/nsScriptElement.h => script/ScriptElement.h} (78%)
 create mode 100644 dom/script/ScriptLoadHandler.cpp
 create mode 100644 dom/script/ScriptLoadHandler.h
 rename dom/{base/nsScriptLoader.cpp => script/ScriptLoader.cpp} (73%)
 rename dom/{base/nsScriptLoader.h => script/ScriptLoader.h} (72%)
 rename dom/{base => script}/ScriptSettings.cpp (100%)
 rename dom/{base => script}/ScriptSettings.h (100%)
 create mode 100644 dom/script/moz.build
 rename dom/{base => script}/nsIScriptElement.h (100%)
 rename dom/{base => script}/nsIScriptLoaderObserver.idl (100%)

diff --git a/dom/base/ImportManager.cpp b/dom/base/ImportManager.cpp
index d0e514b59..1f4d376b3 100644
--- a/dom/base/ImportManager.cpp
+++ b/dom/base/ImportManager.cpp
@@ -6,6 +6,7 @@
 
 #include "ImportManager.h"
 
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/EventListenerManager.h"
 #include "HTMLLinkElement.h"
 #include "nsContentPolicyUtils.h"
@@ -18,7 +19,6 @@
 #include "nsIDOMEvent.h"
 #include "nsIPrincipal.h"
 #include "nsIScriptObjectPrincipal.h"
-#include "nsScriptLoader.h"
 #include "nsNetUtil.h"
 
 //-----------------------------------------------------------------------------
@@ -156,7 +156,7 @@ ImportLoader::Updater::UpdateMainReferrer(uint32_t aNewIdx)
     // Our nearest predecessor has changed. So let's add the ScriptLoader to the
     // new one if there is any. And remove it from the old one.
     RefPtr<ImportManager> manager = mLoader->Manager();
-    nsScriptLoader* loader = mLoader->mDocument->ScriptLoader();
+    ScriptLoader* loader = mLoader->mDocument->ScriptLoader();
     ImportLoader*& pred = mLoader->mBlockingPredecessor;
     ImportLoader* newPred = manager->GetNearestPredecessor(newMainReferrer);
     if (pred) {
@@ -339,7 +339,7 @@ ImportLoader::DispatchEventIfFinished(nsINode* aNode)
 }
 
 void
-ImportLoader::AddBlockedScriptLoader(nsScriptLoader* aScriptLoader)
+ImportLoader::AddBlockedScriptLoader(ScriptLoader* aScriptLoader)
 {
   if (mBlockedScriptLoaders.Contains(aScriptLoader)) {
     return;
@@ -352,7 +352,7 @@ ImportLoader::AddBlockedScriptLoader(nsScriptLoader* aScriptLoader)
 }
 
 bool
-ImportLoader::RemoveBlockedScriptLoader(nsScriptLoader* aScriptLoader)
+ImportLoader::RemoveBlockedScriptLoader(ScriptLoader* aScriptLoader)
 {
   aScriptLoader->RemoveParserBlockingScriptExecutionBlocker();
   return mBlockedScriptLoaders.RemoveElement(aScriptLoader);
diff --git a/dom/base/ImportManager.h b/dom/base/ImportManager.h
index 258d4691c..ccc00125a 100644
--- a/dom/base/ImportManager.h
+++ b/dom/base/ImportManager.h
@@ -45,8 +45,8 @@
 #include "nsIStreamListener.h"
 #include "nsIWeakReferenceUtils.h"
 #include "nsRefPtrHashtable.h"
-#include "nsScriptLoader.h"
 #include "nsURIHashKey.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 class nsIDocument;
 class nsIPrincipal;
@@ -184,8 +184,8 @@ public:
   // and wait for that to run its scripts. We keep track of all the
   // ScriptRunners that are waiting for this import. NOTE: updating
   // the main referrer might change this list.
-  void AddBlockedScriptLoader(nsScriptLoader* aScriptLoader);
-  bool RemoveBlockedScriptLoader(nsScriptLoader* aScriptLoader);
+  void AddBlockedScriptLoader(ScriptLoader* aScriptLoader);
+  bool RemoveBlockedScriptLoader(ScriptLoader* aScriptLoader);
   void SetBlockingPredecessor(ImportLoader* aLoader);
 
 private:
@@ -230,7 +230,7 @@ private:
 
   // List of pending ScriptLoaders that are waiting for this import
   // to finish.
-  nsTArray<RefPtr<nsScriptLoader>> mBlockedScriptLoaders;
+  nsTArray<RefPtr<ScriptLoader>> mBlockedScriptLoaders;
 
   // There is always exactly one referrer link that is flagged as
   // the main referrer the primary link. This is the one that is
diff --git a/dom/base/Location.cpp b/dom/base/Location.cpp
index 1483c32f9..308e9a4ff 100644
--- a/dom/base/Location.cpp
+++ b/dom/base/Location.cpp
@@ -32,9 +32,9 @@
 #include "mozilla/Likely.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsNullPrincipal.h"
-#include "ScriptSettings.h"
 #include "mozilla/Unused.h"
 #include "mozilla/dom/LocationBinding.h"
+#include "mozilla/dom/ScriptSettings.h"
 
 namespace mozilla {
 namespace dom {
diff --git a/dom/base/moz.build b/dom/base/moz.build
index 4b893c678..56a1e60d3 100644
--- a/dom/base/moz.build
+++ b/dom/base/moz.build
@@ -26,7 +26,6 @@ XPIDL_SOURCES += [
     'nsIObjectLoadingContent.idl',
     'nsIRemoteWindowContext.idl',
     'nsIScriptChannel.idl',
-    'nsIScriptLoaderObserver.idl',
     'nsISelection.idl',
     'nsISelectionController.idl',
     'nsISelectionDisplay.idl',
@@ -96,7 +95,6 @@ EXPORTS += [
     'nsINode.h',
     'nsINodeList.h',
     'nsIScriptContext.h',
-    'nsIScriptElement.h',
     'nsIScriptGlobalObject.h',
     'nsIScriptNameSpaceManager.h',
     'nsIScriptObjectPrincipal.h',
@@ -117,7 +115,6 @@ EXPORTS += [
     'nsRange.h',
     'nsReferencedElement.h',
     'nsSandboxFlags.h',
-    'nsScriptLoader.h',
     'nsStructuredCloneContainer.h',
     'nsStubAnimationObserver.h',
     'nsStubDocumentObserver.h',
@@ -208,7 +205,6 @@ EXPORTS.mozilla.dom += [
     'ResponsiveImageSelector.h',
     'SameProcessMessageQueue.h',
     'ScreenOrientation.h',
-    'ScriptSettings.h',
     'ShadowRoot.h',
     'SimpleTreeIterator.h',
     'StructuredCloneHolder.h',
@@ -329,8 +325,6 @@ SOURCES += [
     'nsRange.cpp',
     'nsReferencedElement.cpp',
     'nsScreen.cpp',
-    'nsScriptElement.cpp',
-    'nsScriptLoader.cpp',
     'nsScriptNameSpaceManager.cpp',
     'nsStructuredCloneContainer.cpp',
     'nsStubAnimationObserver.cpp',
@@ -356,7 +350,6 @@ SOURCES += [
     'ResponsiveImageSelector.cpp',
     'SameProcessMessageQueue.cpp',
     'ScreenOrientation.cpp',
-    'ScriptSettings.cpp',
     'ShadowRoot.cpp',
     'StructuredCloneHolder.cpp',
     'StyleScope.cpp',
diff --git a/dom/base/nsContentPermissionHelper.cpp b/dom/base/nsContentPermissionHelper.cpp
index c57fc6233..eaaec2a41 100644
--- a/dom/base/nsContentPermissionHelper.cpp
+++ b/dom/base/nsContentPermissionHelper.cpp
@@ -29,9 +29,8 @@
 #include "nsIDocument.h"
 #include "nsIDOMEvent.h"
 #include "nsWeakPtr.h"
-#include "ScriptSettings.h"
 
-using mozilla::Unused;          // <snicker>
+using mozilla::Unused;
 using namespace mozilla::dom;
 using namespace mozilla;
 
diff --git a/dom/base/nsContentSink.cpp b/dom/base/nsContentSink.cpp
index 490f0ec17..1e6465a1b 100644
--- a/dom/base/nsContentSink.cpp
+++ b/dom/base/nsContentSink.cpp
@@ -10,7 +10,6 @@
  */
 
 #include "nsContentSink.h"
-#include "nsScriptLoader.h"
 #include "nsIDocument.h"
 #include "nsIDOMDocument.h"
 #include "mozilla/css/Loader.h"
@@ -49,6 +48,7 @@
 #include "nsHTMLDNSPrefetch.h"
 #include "nsIObserverService.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "nsParserConstants.h"
 #include "nsSandboxFlags.h"
 
diff --git a/dom/base/nsContentSink.h b/dom/base/nsContentSink.h
index b1a758874..2d914a8d7 100644
--- a/dom/base/nsContentSink.h
+++ b/dom/base/nsContentSink.h
@@ -36,13 +36,16 @@ class nsIAtom;
 class nsIChannel;
 class nsIContent;
 class nsNodeInfoManager;
-class nsScriptLoader;
 class nsIApplicationCache;
 
 namespace mozilla {
 namespace css {
 class Loader;
 } // namespace css
+
+namespace dom {
+class ScriptLoader;
+} // namespace dom
 } // namespace mozilla
 
 #ifdef DEBUG
@@ -273,7 +276,7 @@ protected:
   nsCOMPtr<nsIDocShell>         mDocShell;
   RefPtr<mozilla::css::Loader> mCSSLoader;
   RefPtr<nsNodeInfoManager>   mNodeInfoManager;
-  RefPtr<nsScriptLoader>      mScriptLoader;
+  RefPtr<mozilla::dom::ScriptLoader> mScriptLoader;
 
   // back off timer notification after count
   int32_t mBackoffCount;
diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index 7b280a188..c1e97e7f9 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -1812,7 +1812,7 @@ nsDocument::Init()
   mScopeObject = do_GetWeakReference(global);
   MOZ_ASSERT(mScopeObject);
 
-  mScriptLoader = new nsScriptLoader(this);
+  mScriptLoader = new dom::ScriptLoader(this);
 
   mozilla::HoldJSObjects(this);
 
@@ -4622,7 +4622,7 @@ nsDocument::GetWindowInternal() const
   return win;
 }
 
-nsScriptLoader*
+ScriptLoader*
 nsDocument::ScriptLoader()
 {
   return mScriptLoader;
diff --git a/dom/base/nsDocument.h b/dom/base/nsDocument.h
index 6520d905d..f089e628f 100644
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -31,7 +31,6 @@
 #include "nsJSThingHashtable.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "nsIURI.h"
-#include "nsScriptLoader.h"
 #include "nsIRadioGroupContainer.h"
 #include "nsILayoutHistoryState.h"
 #include "nsIRequest.h"
@@ -60,6 +59,7 @@
 #include "mozilla/MemoryReporting.h"
 #include "mozilla/PendingAnimationTracker.h"
 #include "mozilla/dom/DOMImplementation.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/StyleSheetList.h"
 #include "nsDataHashtable.h"
 #include "mozilla/TimeStamp.h"
@@ -636,7 +636,7 @@ public:
   /**
    * Get the script loader for this document
    */
-  virtual nsScriptLoader* ScriptLoader() override;
+  virtual mozilla::dom::ScriptLoader* ScriptLoader() override;
 
   /**
    * Add/Remove an element to the document's id and name hashes
@@ -1348,7 +1348,7 @@ protected:
 public:
   RefPtr<mozilla::EventListenerManager> mListenerManager;
   RefPtr<nsDOMStyleSheetSetList> mStyleSheetSetList;
-  RefPtr<nsScriptLoader> mScriptLoader;
+  RefPtr<mozilla::dom::ScriptLoader> mScriptLoader;
   nsDocHeaderData* mHeaderData;
   /* mIdentifierMap works as follows for IDs:
    * 1) Attribute changes affect the table immediately (removing and adding
diff --git a/dom/base/nsFrameMessageManager.cpp b/dom/base/nsFrameMessageManager.cpp
index bba4232aa..331931f19 100644
--- a/dom/base/nsFrameMessageManager.cpp
+++ b/dom/base/nsFrameMessageManager.cpp
@@ -19,7 +19,6 @@
 #include "nsJSUtils.h"
 #include "nsJSPrincipals.h"
 #include "nsNetUtil.h"
-#include "nsScriptLoader.h"
 #include "nsFrameLoader.h"
 #include "nsIXULRuntime.h"
 #include "nsIScriptError.h"
@@ -38,6 +37,7 @@
 #include "mozilla/dom/PermissionMessageUtils.h"
 #include "mozilla/dom/ProcessGlobal.h"
 #include "mozilla/dom/SameProcessMessageQueue.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/ipc/BlobChild.h"
 #include "mozilla/dom/ipc/BlobParent.h"
@@ -1786,9 +1786,9 @@ nsMessageManagerScriptExecutor::TryCacheLoadAndCompileScript(
     if (NS_FAILED(NS_ReadInputStreamToString(input, buffer, avail))) {
       return;
     }
-    nsScriptLoader::ConvertToUTF16(channel, (uint8_t*)buffer.get(), avail,
-                                   EmptyString(), nullptr,
-                                   dataStringBuf, dataStringLength);
+    ScriptLoader::ConvertToUTF16(channel, (uint8_t*)buffer.get(), avail,
+                                 EmptyString(), nullptr,
+                                 dataStringBuf, dataStringLength);
   }
 
   JS::SourceBufferHolder srcBuf(dataStringBuf, dataStringLength,
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index 69643762c..acd596a44 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -62,7 +62,7 @@
 #include "nsReadableUtils.h"
 #include "nsDOMClassInfo.h"
 #include "nsJSEnvironment.h"
-#include "ScriptSettings.h"
+#include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/Likely.h"
 #include "mozilla/Sprintf.h"
diff --git a/dom/base/nsIDocument.h b/dom/base/nsIDocument.h
index b4fda21c1..4d2063ce7 100644
--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -93,7 +93,6 @@ class nsIVariant;
 class nsViewManager;
 class nsPresContext;
 class nsRange;
-class nsScriptLoader;
 class nsSMILAnimationController;
 class nsTextNode;
 class nsWindowSizes;
@@ -153,6 +152,7 @@ enum class OrientationType : uint32_t;
 class ProcessingInstruction;
 class Promise;
 class Selection;
+class ScriptLoader;
 class StyleSheetList;
 class SVGDocument;
 class SVGSVGElement;
@@ -1283,7 +1283,7 @@ public:
   /**
    * Get the script loader for this document
    */
-  virtual nsScriptLoader* ScriptLoader() = 0;
+  virtual mozilla::dom::ScriptLoader* ScriptLoader() = 0;
 
   /**
    * Add/Remove an element to the document's id and name hashes
diff --git a/dom/base/nsInProcessTabChildGlobal.cpp b/dom/base/nsInProcessTabChildGlobal.cpp
index 9885b41a8..4cc3c9ce9 100644
--- a/dom/base/nsInProcessTabChildGlobal.cpp
+++ b/dom/base/nsInProcessTabChildGlobal.cpp
@@ -11,13 +11,13 @@
 #include "nsIComponentManager.h"
 #include "nsIServiceManager.h"
 #include "nsComponentManagerUtils.h"
-#include "nsScriptLoader.h"
 #include "nsFrameLoader.h"
 #include "xpcpublic.h"
 #include "nsIMozBrowserFrame.h"
 #include "nsDOMClassInfoID.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/dom/SameProcessMessageQueue.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index efea3ee40..605b1917f 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -37,7 +37,6 @@
 #include "nsXPCOMCIDInternal.h"
 #include "nsIXULRuntime.h"
 #include "nsTextFormatter.h"
-#include "ScriptSettings.h"
 
 #include "xpcpublic.h"
 
@@ -55,6 +54,7 @@
 #include "mozilla/dom/DOMException.h"
 #include "mozilla/dom/DOMExceptionBinding.h"
 #include "mozilla/dom/ErrorEvent.h"
+#include "mozilla/dom/ScriptSettings.h"
 #include "nsAXPCNativeCallContext.h"
 #include "mozilla/CycleCollectedJSContext.h"
 #include "mozilla/Telemetry.h"
diff --git a/dom/base/nsPlainTextSerializer.h b/dom/base/nsPlainTextSerializer.h
index 650a8e3e7..58aeb4207 100644
--- a/dom/base/nsPlainTextSerializer.h
+++ b/dom/base/nsPlainTextSerializer.h
@@ -16,6 +16,7 @@
 #include "mozilla/Attributes.h"
 #include "nsCOMPtr.h"
 #include "nsIAtom.h"
+#include "nsCycleCollectionParticipant.h"
 #include "nsIContentSerializer.h"
 #include "nsIDocumentEncoder.h"
 #include "nsILineBreaker.h"
diff --git a/dom/console/Console.cpp b/dom/console/Console.cpp
index b174172e0..119a259fe 100644
--- a/dom/console/Console.cpp
+++ b/dom/console/Console.cpp
@@ -12,6 +12,7 @@
 #include "mozilla/dom/File.h"
 #include "mozilla/dom/FunctionBinding.h"
 #include "mozilla/dom/Performance.h"
+#include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/StructuredCloneHolder.h"
 #include "mozilla/dom/ToJSValue.h"
 #include "mozilla/dom/WorkletGlobalScope.h"
@@ -22,7 +23,6 @@
 #include "nsGlobalWindow.h"
 #include "nsJSUtils.h"
 #include "nsNetUtil.h"
-#include "ScriptSettings.h"
 #include "WorkerPrivate.h"
 #include "WorkerRunnable.h"
 #include "WorkerScope.h"
diff --git a/dom/events/DOMEventTargetHelper.cpp b/dom/events/DOMEventTargetHelper.cpp
index f534f119c..3d162b01e 100644
--- a/dom/events/DOMEventTargetHelper.cpp
+++ b/dom/events/DOMEventTargetHelper.cpp
@@ -8,7 +8,7 @@
 #include "nsIDocument.h"
 #include "mozilla/Sprintf.h"
 #include "nsGlobalWindow.h"
-#include "ScriptSettings.h"
+#include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventListenerManager.h"
diff --git a/dom/html/HTMLScriptElement.cpp b/dom/html/HTMLScriptElement.cpp
index a1bea94d9..5b727280f 100644
--- a/dom/html/HTMLScriptElement.cpp
+++ b/dom/html/HTMLScriptElement.cpp
@@ -37,7 +37,7 @@ HTMLScriptElement::WrapNode(JSContext *aCx, JS::Handle<JSObject*> aGivenProto)
 HTMLScriptElement::HTMLScriptElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo,
                                      FromParser aFromParser)
   : nsGenericHTMLElement(aNodeInfo)
-  , nsScriptElement(aFromParser)
+  , ScriptElement(aFromParser)
 {
   AddMutationObserver(this);
 }
diff --git a/dom/html/HTMLScriptElement.h b/dom/html/HTMLScriptElement.h
index bd446fa97..6edeb9832 100644
--- a/dom/html/HTMLScriptElement.h
+++ b/dom/html/HTMLScriptElement.h
@@ -8,16 +8,16 @@
 #define mozilla_dom_HTMLScriptElement_h
 
 #include "nsIDOMHTMLScriptElement.h"
-#include "nsScriptElement.h"
 #include "nsGenericHTMLElement.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/dom/ScriptElement.h"
 
 namespace mozilla {
 namespace dom {
 
 class HTMLScriptElement final : public nsGenericHTMLElement,
                                 public nsIDOMHTMLScriptElement,
-                                public nsScriptElement
+                                public ScriptElement
 {
 public:
   using Element::GetText;
@@ -98,7 +98,8 @@ protected:
   virtual ~HTMLScriptElement();
 
   virtual JSObject* WrapNode(JSContext *aCx, JS::Handle<JSObject*> aGivenProto) override;
-  // nsScriptElement
+
+  // ScriptElement
   virtual bool HasScriptContent() override;
 };
 
diff --git a/dom/html/nsGenericHTMLElement.cpp b/dom/html/nsGenericHTMLElement.cpp
index 17dba6da9..b52e61ce6 100644
--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -48,7 +48,6 @@
 #include "nsIDocShell.h"
 #include "nsNameSpaceManager.h"
 #include "nsError.h"
-#include "nsScriptLoader.h"
 #include "nsRuleData.h"
 #include "nsIPrincipal.h"
 #include "nsContainerFrame.h"
@@ -92,6 +91,7 @@
 #include "mozilla/dom/FromParser.h"
 #include "mozilla/dom/Link.h"
 #include "mozilla/BloomFilter.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 #include "nsVariant.h"
 #include "nsDOMTokenList.h"
diff --git a/dom/html/nsHTMLContentSink.cpp b/dom/html/nsHTMLContentSink.cpp
index eb22b772f..f7e380f40 100644
--- a/dom/html/nsHTMLContentSink.cpp
+++ b/dom/html/nsHTMLContentSink.cpp
@@ -20,10 +20,10 @@
 #include "nsIHTMLContentSink.h"
 #include "nsIInterfaceRequestor.h"
 #include "nsIInterfaceRequestorUtils.h"
-#include "nsScriptLoader.h"
 #include "nsIURI.h"
 #include "nsIContentViewer.h"
 #include "mozilla/dom/NodeInfo.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "nsToken.h"
 #include "nsIAppShell.h"
 #include "nsCRT.h"
diff --git a/dom/messagechannel/MessagePort.cpp b/dom/messagechannel/MessagePort.cpp
index 56204da99..fcbe36a72 100644
--- a/dom/messagechannel/MessagePort.cpp
+++ b/dom/messagechannel/MessagePort.cpp
@@ -16,6 +16,7 @@
 #include "mozilla/dom/MessagePortBinding.h"
 #include "mozilla/dom/MessagePortChild.h"
 #include "mozilla/dom/PMessagePort.h"
+#include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/StructuredCloneTags.h"
 #include "mozilla/dom/WorkerPrivate.h"
 #include "mozilla/dom/WorkerScope.h"
@@ -28,7 +29,6 @@
 #include "nsContentUtils.h"
 #include "nsGlobalWindow.h"
 #include "nsPresContext.h"
-#include "ScriptSettings.h"
 #include "SharedMessagePortMessage.h"
 
 #include "nsIBFCacheEntry.h"
diff --git a/dom/moz.build b/dom/moz.build
index 8a958982f..7888ccd69 100644
--- a/dom/moz.build
+++ b/dom/moz.build
@@ -100,6 +100,7 @@ DIRS += [
     'performance',
     'xhr',
     'worklet',
+    'script',
 ]
 
 if CONFIG['OS_ARCH'] == 'WINNT':
diff --git a/dom/script/ModuleLoadRequest.cpp b/dom/script/ModuleLoadRequest.cpp
new file mode 100644
index 000000000..e72edca2e
--- /dev/null
+++ b/dom/script/ModuleLoadRequest.cpp
@@ -0,0 +1,102 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ModuleLoadRequest.h"
+#include "ModuleScript.h"
+#include "ScriptLoader.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(ModuleLoadRequest)
+NS_INTERFACE_MAP_END_INHERITING(ScriptLoadRequest)
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(ModuleLoadRequest, ScriptLoadRequest,
+                                   mBaseURL,
+                                   mLoader,
+                                   mParent,
+                                   mModuleScript,
+                                   mImports)
+
+NS_IMPL_ADDREF_INHERITED(ModuleLoadRequest, ScriptLoadRequest)
+NS_IMPL_RELEASE_INHERITED(ModuleLoadRequest, ScriptLoadRequest)
+
+ModuleLoadRequest::ModuleLoadRequest(nsIScriptElement* aElement,
+                                     uint32_t aVersion,
+                                     CORSMode aCORSMode,
+                                     const SRIMetadata &aIntegrity,
+                                     ScriptLoader* aLoader)
+  : ScriptLoadRequest(ScriptKind::Module,
+                      aElement,
+                      aVersion,
+                      aCORSMode,
+                      aIntegrity),
+    mIsTopLevel(true),
+    mLoader(aLoader)
+{}
+
+void ModuleLoadRequest::Cancel()
+{
+  ScriptLoadRequest::Cancel();
+  mModuleScript = nullptr;
+  mProgress = ScriptLoadRequest::Progress::Ready;
+  for (size_t i = 0; i < mImports.Length(); i++) {
+    mImports[i]->Cancel();
+  }
+  mReady.RejectIfExists(NS_ERROR_FAILURE, __func__);
+}
+
+void
+ModuleLoadRequest::SetReady()
+{
+#ifdef DEBUG
+  for (size_t i = 0; i < mImports.Length(); i++) {
+    MOZ_ASSERT(mImports[i]->IsReadyToRun());
+  }
+#endif
+
+  ScriptLoadRequest::SetReady();
+  mReady.ResolveIfExists(true, __func__);
+}
+
+void
+ModuleLoadRequest::ModuleLoaded()
+{
+  // A module that was found to be marked as fetching in the module map has now
+  // been loaded.
+
+  mModuleScript = mLoader->GetFetchedModule(mURI);
+  mLoader->StartFetchingModuleDependencies(this);
+}
+
+void
+ModuleLoadRequest::DependenciesLoaded()
+{
+  // The module and all of its dependencies have been successfully fetched and
+  // compiled.
+
+  if (!mLoader->InstantiateModuleTree(this)) {
+    LoadFailed();
+    return;
+  }
+
+  SetReady();
+  mLoader->ProcessLoadedModuleTree(this);
+  mLoader = nullptr;
+  mParent = nullptr;
+}
+
+void
+ModuleLoadRequest::LoadFailed()
+{
+  Cancel();
+  mLoader->ProcessLoadedModuleTree(this);
+  mLoader = nullptr;
+  mParent = nullptr;
+}
+
+} // dom namespace
+} // mozilla namespace
\ No newline at end of file
diff --git a/dom/script/ModuleLoadRequest.h b/dom/script/ModuleLoadRequest.h
new file mode 100644
index 000000000..0119fad38
--- /dev/null
+++ b/dom/script/ModuleLoadRequest.h
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ModuleLoadRequest_h
+#define mozilla_dom_ModuleLoadRequest_h
+
+#include "mozilla/dom/ScriptLoader.h"
+#include "mozilla/MozPromise.h"
+
+namespace mozilla {
+namespace dom {
+
+class ModuleScript;
+class ScriptLoader;
+
+// A load request for a module, created for every top level module script and
+// every module import. Load request can share a ModuleScript if there are
+// multiple imports of the same module.
+
+class ModuleLoadRequest final : public ScriptLoadRequest
+{
+  ~ModuleLoadRequest() {}
+
+  ModuleLoadRequest(const ModuleLoadRequest& aOther) = delete;
+  ModuleLoadRequest(ModuleLoadRequest&& aOther) = delete;
+
+public:
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(ModuleLoadRequest, ScriptLoadRequest)
+
+  ModuleLoadRequest(nsIScriptElement* aElement,
+                    uint32_t aVersion,
+                    CORSMode aCORSMode,
+                    const SRIMetadata& aIntegrity,
+                    ScriptLoader* aLoader);
+
+  bool IsTopLevel() const {
+    return mIsTopLevel;
+  }
+
+  void SetReady() override;
+  void Cancel() override;
+
+  void ModuleLoaded();
+  void DependenciesLoaded();
+  void LoadFailed();
+
+  // Is this a request for a top level module script or an import?
+  bool mIsTopLevel;
+
+  // The base URL used for resolving relative module imports.
+  nsCOMPtr<nsIURI> mBaseURL;
+
+  // Pointer to the script loader, used to trigger actions when the module load
+  // finishes.
+  RefPtr<ScriptLoader> mLoader;
+
+  // The importing module, or nullptr for top level module scripts.  Used to
+  // implement the ancestor list checked when fetching module dependencies.
+  RefPtr<ModuleLoadRequest> mParent;
+
+  // Set to a module script object after a successful load or nullptr on
+  // failure.
+  RefPtr<ModuleScript> mModuleScript;
+
+  // A promise that is completed on successful load of this module and all of
+  // its dependencies, indicating that the module is ready for instantiation and
+  // evaluation.
+  MozPromiseHolder<GenericPromise> mReady;
+
+  // Array of imported modules.
+  nsTArray<RefPtr<ModuleLoadRequest>> mImports;
+};
+
+} // dom namespace
+} // mozilla namespace
+
+#endif // mozilla_dom_ModuleLoadRequest_h
\ No newline at end of file
diff --git a/dom/script/ModuleScript.cpp b/dom/script/ModuleScript.cpp
new file mode 100644
index 000000000..34ef4dec4
--- /dev/null
+++ b/dom/script/ModuleScript.cpp
@@ -0,0 +1,100 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * A class that handles loading and evaluation of <script> elements.
+ */
+
+#include "ModuleScript.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "ScriptLoader.h"
+
+namespace mozilla {
+namespace dom {
+
+// A single module script.  May be used to satisfy multiple load requests.
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ModuleScript)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(ModuleScript)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ModuleScript)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mLoader)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mBaseURL)
+  tmp->UnlinkModuleRecord();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(ModuleScript)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mLoader)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(ModuleScript)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mModuleRecord)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mException)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ModuleScript)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ModuleScript)
+
+ModuleScript::ModuleScript(ScriptLoader *aLoader, nsIURI* aBaseURL,
+                           JS::Handle<JSObject*> aModuleRecord)
+ : mLoader(aLoader),
+   mBaseURL(aBaseURL),
+   mModuleRecord(aModuleRecord),
+   mInstantiationState(Uninstantiated)
+{
+  MOZ_ASSERT(mLoader);
+  MOZ_ASSERT(mBaseURL);
+  MOZ_ASSERT(mModuleRecord);
+  MOZ_ASSERT(mException.isUndefined());
+
+  // Make module's host defined field point to this module script object.
+  // This is cleared in the UnlinkModuleRecord().
+  JS::SetModuleHostDefinedField(mModuleRecord, JS::PrivateValue(this));
+  HoldJSObjects(this);
+}
+
+void
+ModuleScript::UnlinkModuleRecord()
+{
+  // Remove module's back reference to this object request if present.
+  if (mModuleRecord) {
+    MOZ_ASSERT(JS::GetModuleHostDefinedField(mModuleRecord).toPrivate() ==
+               this);
+    JS::SetModuleHostDefinedField(mModuleRecord, JS::UndefinedValue());
+  }
+  mModuleRecord = nullptr;
+  mException.setUndefined();
+}
+
+ModuleScript::~ModuleScript()
+{
+  if (mModuleRecord) {
+    // The object may be destroyed without being unlinked first.
+    UnlinkModuleRecord();
+  }
+  DropJSObjects(this);
+}
+
+void
+ModuleScript::SetInstantiationResult(JS::Handle<JS::Value> aMaybeException)
+{
+  MOZ_ASSERT(mInstantiationState == Uninstantiated);
+  MOZ_ASSERT(mModuleRecord);
+  MOZ_ASSERT(mException.isUndefined());
+
+  if (aMaybeException.isUndefined()) {
+    mInstantiationState = Instantiated;
+  } else {
+    mModuleRecord = nullptr;
+    mException = aMaybeException;
+    mInstantiationState = Errored;
+  }
+}
+
+} // dom namespace
+} // mozilla namespace
diff --git a/dom/script/ModuleScript.h b/dom/script/ModuleScript.h
new file mode 100644
index 000000000..dd0d07e84
--- /dev/null
+++ b/dom/script/ModuleScript.h
@@ -0,0 +1,67 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ModuleScript_h
+#define mozilla_dom_ModuleScript_h
+
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "jsapi.h"
+
+class nsIURI;
+
+namespace mozilla {
+namespace dom {
+
+class ScriptLoader;
+
+class ModuleScript final : public nsISupports
+{
+  enum InstantiationState {
+    Uninstantiated,
+    Instantiated,
+    Errored
+  };
+
+  RefPtr<ScriptLoader> mLoader;
+  nsCOMPtr<nsIURI> mBaseURL;
+  JS::Heap<JSObject*> mModuleRecord;
+  JS::Heap<JS::Value> mException;
+  InstantiationState mInstantiationState;
+
+  ~ModuleScript();
+
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ModuleScript)
+
+  ModuleScript(ScriptLoader* aLoader,
+               nsIURI* aBaseURL,
+               JS::Handle<JSObject*> aModuleRecord);
+
+  ScriptLoader* Loader() const { return mLoader; }
+  JSObject* ModuleRecord() const { return mModuleRecord; }
+  JS::Value Exception() const { return mException; }
+  nsIURI* BaseURL() const { return mBaseURL; }
+
+  void SetInstantiationResult(JS::Handle<JS::Value> aMaybeException);
+  bool IsUninstantiated() const {
+    return mInstantiationState == Uninstantiated;
+  }
+  bool IsInstantiated() const {
+    return mInstantiationState == Instantiated;
+  }
+  bool InstantiationFailed() const {
+    return mInstantiationState == Errored;
+  }
+
+  void UnlinkModuleRecord();
+};
+
+} // dom namespace
+} // mozilla namespace
+
+#endif // mozilla_dom_ModuleScript_h
\ No newline at end of file
diff --git a/dom/base/nsScriptElement.cpp b/dom/script/ScriptElement.cpp
similarity index 64%
rename from dom/base/nsScriptElement.cpp
rename to dom/script/ScriptElement.cpp
index ebeb18f81..0cb17dcb0 100644
--- a/dom/base/nsScriptElement.cpp
+++ b/dom/script/ScriptElement.cpp
@@ -4,13 +4,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#include "nsScriptElement.h"
+#include "ScriptElement.h"
+#include "ScriptLoader.h"
 #include "mozilla/BasicEvents.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/dom/Element.h"
 #include "nsContentUtils.h"
 #include "nsPresContext.h"
-#include "nsScriptLoader.h"
 #include "nsIParser.h"
 #include "nsGkAtoms.h"
 #include "nsContentSink.h"
@@ -19,11 +19,11 @@ using namespace mozilla;
 using namespace mozilla::dom;
 
 NS_IMETHODIMP
-nsScriptElement::ScriptAvailable(nsresult aResult,
-                                 nsIScriptElement *aElement,
-                                 bool aIsInline,
-                                 nsIURI *aURI,
-                                 int32_t aLineNo)
+ScriptElement::ScriptAvailable(nsresult aResult,
+                               nsIScriptElement *aElement,
+                               bool aIsInline,
+                               nsIURI *aURI,
+                               int32_t aLineNo)
 {
   if (!aIsInline && NS_FAILED(aResult)) {
     nsCOMPtr<nsIParser> parser = do_QueryReferent(mCreatorParser);
@@ -40,7 +40,7 @@ nsScriptElement::ScriptAvailable(nsresult aResult,
 }
 
 /* virtual */ nsresult
-nsScriptElement::FireErrorEvent()
+ScriptElement::FireErrorEvent()
 {
   nsCOMPtr<nsIContent> cont =
     do_QueryInterface((nsIScriptElement*) this);
@@ -53,9 +53,9 @@ nsScriptElement::FireErrorEvent()
 }
 
 NS_IMETHODIMP
-nsScriptElement::ScriptEvaluated(nsresult aResult,
-                                 nsIScriptElement *aElement,
-                                 bool aIsInline)
+ScriptElement::ScriptEvaluated(nsresult aResult,
+                               nsIScriptElement *aElement,
+                               bool aIsInline)
 {
   nsresult rv = NS_OK;
   if (!aIsInline) {
@@ -78,44 +78,44 @@ nsScriptElement::ScriptEvaluated(nsresult aResult,
 }
 
 void
-nsScriptElement::CharacterDataChanged(nsIDocument *aDocument,
-                                      nsIContent* aContent,
-                                      CharacterDataChangeInfo* aInfo)
+ScriptElement::CharacterDataChanged(nsIDocument *aDocument,
+                                    nsIContent* aContent,
+                                    CharacterDataChangeInfo* aInfo)
 {
   MaybeProcessScript();
 }
 
 void
-nsScriptElement::AttributeChanged(nsIDocument* aDocument,
-                                  Element* aElement,
-                                  int32_t aNameSpaceID,
-                                  nsIAtom* aAttribute,
-                                  int32_t aModType,
-                                  const nsAttrValue* aOldValue)
+ScriptElement::AttributeChanged(nsIDocument* aDocument,
+                                Element* aElement,
+                                int32_t aNameSpaceID,
+                                nsIAtom* aAttribute,
+                                int32_t aModType,
+                                const nsAttrValue* aOldValue)
 {
   MaybeProcessScript();
 }
 
 void
-nsScriptElement::ContentAppended(nsIDocument* aDocument,
-                                 nsIContent* aContainer,
-                                 nsIContent* aFirstNewContent,
-                                 int32_t aNewIndexInContainer)
+ScriptElement::ContentAppended(nsIDocument* aDocument,
+                               nsIContent* aContainer,
+                               nsIContent* aFirstNewContent,
+                               int32_t aNewIndexInContainer)
 {
   MaybeProcessScript();
 }
 
 void
-nsScriptElement::ContentInserted(nsIDocument *aDocument,
-                                 nsIContent* aContainer,
-                                 nsIContent* aChild,
-                                 int32_t aIndexInContainer)
+ScriptElement::ContentInserted(nsIDocument *aDocument,
+                               nsIContent* aContainer,
+                               nsIContent* aChild,
+                               int32_t aIndexInContainer)
 {
   MaybeProcessScript();
 }
 
 bool
-nsScriptElement::MaybeProcessScript()
+ScriptElement::MaybeProcessScript()
 {
   nsCOMPtr<nsIContent> cont =
     do_QueryInterface((nsIScriptElement*) this);
@@ -145,6 +145,6 @@ nsScriptElement::MaybeProcessScript()
     }
   }
 
-  RefPtr<nsScriptLoader> loader = ownerDoc->ScriptLoader();
+  RefPtr<ScriptLoader> loader = ownerDoc->ScriptLoader();
   return loader->ProcessScriptElement(this);
 }
diff --git a/dom/base/nsScriptElement.h b/dom/script/ScriptElement.h
similarity index 78%
rename from dom/base/nsScriptElement.h
rename to dom/script/ScriptElement.h
index 4a2a584ac..0babda674 100644
--- a/dom/base/nsScriptElement.h
+++ b/dom/script/ScriptElement.h
@@ -4,22 +4,25 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#ifndef nsScriptElement_h
-#define nsScriptElement_h
+#ifndef mozilla_dom_ScriptElement_h
+#define mozilla_dom_ScriptElement_h
 
 #include "mozilla/Attributes.h"
 #include "nsIScriptLoaderObserver.h"
 #include "nsIScriptElement.h"
 #include "nsStubMutationObserver.h"
 
+namespace mozilla {
+namespace dom {
+
 /**
  * Baseclass useful for script elements (such as <xhtml:script> and
  * <svg:script>). Currently the class assumes that only the 'src'
  * attribute and the children of the class affect what script to execute.
  */
 
-class nsScriptElement : public nsIScriptElement,
-                        public nsStubMutationObserver
+class ScriptElement : public nsIScriptElement,
+                      public nsStubMutationObserver
 {
 public:
   // nsIScriptLoaderObserver
@@ -31,7 +34,7 @@ public:
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTAPPENDED
   NS_DECL_NSIMUTATIONOBSERVER_CONTENTINSERTED
 
-  explicit nsScriptElement(mozilla::dom::FromParser aFromParser)
+  explicit ScriptElement(FromParser aFromParser)
     : nsIScriptElement(aFromParser)
   {
   }
@@ -49,4 +52,7 @@ protected:
   virtual bool MaybeProcessScript() override;
 };
 
-#endif // nsScriptElement_h
+} // dom namespace
+} // mozilla namespace
+
+#endif // mozilla_dom_ScriptElement_h
diff --git a/dom/script/ScriptLoadHandler.cpp b/dom/script/ScriptLoadHandler.cpp
new file mode 100644
index 000000000..80fb70f6a
--- /dev/null
+++ b/dom/script/ScriptLoadHandler.cpp
@@ -0,0 +1,216 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * A class that handles loading and evaluation of <script> elements.
+ */
+
+#include "ScriptLoadHandler.h"
+#include "ScriptLoader.h"
+#include "nsContentUtils.h"
+
+#include "mozilla/dom/EncodingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+ScriptLoadHandler::ScriptLoadHandler(ScriptLoader *aScriptLoader,
+                                     ScriptLoadRequest *aRequest,
+                                     mozilla::dom::SRICheckDataVerifier *aSRIDataVerifier)
+  : mScriptLoader(aScriptLoader),
+    mRequest(aRequest),
+    mSRIDataVerifier(aSRIDataVerifier),
+    mSRIStatus(NS_OK),
+    mDecoder(),
+    mBuffer()
+{}
+
+ScriptLoadHandler::~ScriptLoadHandler()
+{}
+
+NS_IMPL_ISUPPORTS(ScriptLoadHandler, nsIIncrementalStreamLoaderObserver)
+
+NS_IMETHODIMP
+ScriptLoadHandler::OnIncrementalData(nsIIncrementalStreamLoader* aLoader,
+                                     nsISupports* aContext,
+                                     uint32_t aDataLength,
+                                     const uint8_t* aData,
+                                     uint32_t *aConsumedLength)
+{
+  if (mRequest->IsCanceled()) {
+    // If request cancelled, ignore any incoming data.
+    *aConsumedLength = aDataLength;
+    return NS_OK;
+  }
+
+  if (!EnsureDecoder(aLoader, aData, aDataLength,
+                     /* aEndOfStream = */ false)) {
+    return NS_OK;
+  }
+
+  // Below we will/shall consume entire data chunk.
+  *aConsumedLength = aDataLength;
+
+  // Decoder has already been initialized. -- trying to decode all loaded bytes.
+  nsresult rv = TryDecodeRawData(aData, aDataLength,
+                                 /* aEndOfStream = */ false);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // If SRI is required for this load, appending new bytes to the hash.
+  if (mSRIDataVerifier && NS_SUCCEEDED(mSRIStatus)) {
+    mSRIStatus = mSRIDataVerifier->Update(aDataLength, aData);
+  }
+
+  return rv;
+}
+
+nsresult
+ScriptLoadHandler::TryDecodeRawData(const uint8_t* aData,
+                                    uint32_t aDataLength,
+                                    bool aEndOfStream)
+{
+  int32_t srcLen = aDataLength;
+  const char* src = reinterpret_cast<const char *>(aData);
+  int32_t dstLen;
+  nsresult rv =
+    mDecoder->GetMaxLength(src, srcLen, &dstLen);
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  uint32_t haveRead = mBuffer.length();
+
+  CheckedInt<uint32_t> capacity = haveRead;
+  capacity += dstLen;
+
+  if (!capacity.isValid() || !mBuffer.reserve(capacity.value())) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  rv = mDecoder->Convert(src,
+                         &srcLen,
+                         mBuffer.begin() + haveRead,
+                         &dstLen);
+
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  haveRead += dstLen;
+  MOZ_ASSERT(haveRead <= capacity.value(), "mDecoder produced more data than expected");
+  MOZ_ALWAYS_TRUE(mBuffer.resizeUninitialized(haveRead));
+
+  return NS_OK;
+}
+
+bool
+ScriptLoadHandler::EnsureDecoder(nsIIncrementalStreamLoader *aLoader,
+                                 const uint8_t* aData,
+                                 uint32_t aDataLength,
+                                 bool aEndOfStream)
+{
+  // Check if decoder has already been created.
+  if (mDecoder) {
+    return true;
+  }
+
+  nsAutoCString charset;
+
+  // JavaScript modules are always UTF-8.
+  if (mRequest->IsModuleRequest()) {
+    charset = "UTF-8";
+    mDecoder = EncodingUtils::DecoderForEncoding(charset);
+    return true;
+  }
+
+  // Determine if BOM check should be done.  This occurs either
+  // if end-of-stream has been reached, or at least 3 bytes have
+  // been read from input.
+  if (!aEndOfStream && (aDataLength < 3)) {
+    return false;
+  }
+
+  // Do BOM detection.
+  if (nsContentUtils::CheckForBOM(aData, aDataLength, charset)) {
+    mDecoder = EncodingUtils::DecoderForEncoding(charset);
+    return true;
+  }
+
+  // BOM detection failed, check content stream for charset.
+  nsCOMPtr<nsIRequest> req;
+  nsresult rv = aLoader->GetRequest(getter_AddRefs(req));
+  NS_ASSERTION(req, "StreamLoader's request went away prematurely");
+  NS_ENSURE_SUCCESS(rv, false);
+
+  nsCOMPtr<nsIChannel> channel = do_QueryInterface(req);
+
+  if (channel &&
+      NS_SUCCEEDED(channel->GetContentCharset(charset)) &&
+      EncodingUtils::FindEncodingForLabel(charset, charset)) {
+    mDecoder = EncodingUtils::DecoderForEncoding(charset);
+    return true;
+  }
+
+  // Check the hint charset from the script element or preload
+  // request.
+  nsAutoString hintCharset;
+  if (!mRequest->IsPreload()) {
+    mRequest->mElement->GetScriptCharset(hintCharset);
+  } else {
+    nsTArray<ScriptLoader::PreloadInfo>::index_type i =
+      mScriptLoader->mPreloads.IndexOf(mRequest, 0,
+            ScriptLoader::PreloadRequestComparator());
+
+    NS_ASSERTION(i != mScriptLoader->mPreloads.NoIndex,
+                 "Incorrect preload bookkeeping");
+    hintCharset = mScriptLoader->mPreloads[i].mCharset;
+  }
+
+  if (EncodingUtils::FindEncodingForLabel(hintCharset, charset)) {
+    mDecoder = EncodingUtils::DecoderForEncoding(charset);
+    return true;
+  }
+
+  // Get the charset from the charset of the document.
+  if (mScriptLoader->mDocument) {
+    charset = mScriptLoader->mDocument->GetDocumentCharacterSet();
+    mDecoder = EncodingUtils::DecoderForEncoding(charset);
+    return true;
+  }
+
+  // Curiously, there are various callers that don't pass aDocument. The
+  // fallback in the old code was ISO-8859-1, which behaved like
+  // windows-1252. Saying windows-1252 for clarity and for compliance
+  // with the Encoding Standard.
+  charset = "windows-1252";
+  mDecoder = EncodingUtils::DecoderForEncoding(charset);
+  return true;
+}
+
+NS_IMETHODIMP
+ScriptLoadHandler::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
+                                    nsISupports* aContext,
+                                    nsresult aStatus,
+                                    uint32_t aDataLength,
+                                    const uint8_t* aData)
+{
+  if (!mRequest->IsCanceled()) {
+    DebugOnly<bool> encoderSet =
+      EnsureDecoder(aLoader, aData, aDataLength, /* aEndOfStream = */ true);
+    MOZ_ASSERT(encoderSet);
+    DebugOnly<nsresult> rv = TryDecodeRawData(aData, aDataLength,
+                                              /* aEndOfStream = */ true);
+
+    // If SRI is required for this load, appending new bytes to the hash.
+    if (mSRIDataVerifier && NS_SUCCEEDED(mSRIStatus)) {
+      mSRIStatus = mSRIDataVerifier->Update(aDataLength, aData);
+    }
+  }
+
+  // we have to mediate and use mRequest.
+  return mScriptLoader->OnStreamComplete(aLoader, mRequest, aStatus, mSRIStatus,
+                                         mBuffer, mSRIDataVerifier);
+}
+
+} // dom namespace
+} // mozilla namespace
\ No newline at end of file
diff --git a/dom/script/ScriptLoadHandler.h b/dom/script/ScriptLoadHandler.h
new file mode 100644
index 000000000..b70f87397
--- /dev/null
+++ b/dom/script/ScriptLoadHandler.h
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * A class that handles loading and evaluation of <script> elements.
+ */
+
+#ifndef mozilla_dom_ScriptLoadHandler_h
+#define mozilla_dom_ScriptLoadHandler_h
+
+#include "nsIIncrementalStreamLoader.h"
+#include "nsIUnicodeDecoder.h"
+#include "nsAutoPtr.h"
+#include "mozilla/Vector.h"
+
+namespace mozilla {
+namespace dom {
+
+class ScriptLoadRequest;
+class ScriptLoader;
+class SRICheckDataVerifier;
+
+class ScriptLoadHandler final : public nsIIncrementalStreamLoaderObserver
+{
+public:
+  explicit ScriptLoadHandler(ScriptLoader* aScriptLoader,
+                             ScriptLoadRequest* aRequest,
+                             SRICheckDataVerifier* aSRIDataVerifier);
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIINCREMENTALSTREAMLOADEROBSERVER
+
+private:
+  virtual ~ScriptLoadHandler();
+
+  /*
+   * Try to decode some raw data.
+   */
+  nsresult TryDecodeRawData(const uint8_t* aData, uint32_t aDataLength,
+                            bool aEndOfStream);
+
+  /*
+   * Discover the charset by looking at the stream data, the script
+   * tag, and other indicators.  Returns true if charset has been
+   * discovered.
+   */
+  bool EnsureDecoder(nsIIncrementalStreamLoader *aLoader,
+                     const uint8_t* aData, uint32_t aDataLength,
+                     bool aEndOfStream);
+
+  // ScriptLoader which will handle the parsed script.
+  RefPtr<ScriptLoader>        mScriptLoader;
+
+  // The ScriptLoadRequest for this load.
+  RefPtr<ScriptLoadRequest>   mRequest;
+
+  // SRI data verifier.
+  nsAutoPtr<SRICheckDataVerifier> mSRIDataVerifier;
+
+  // Status of SRI data operations.
+  nsresult                      mSRIStatus;
+
+  // Unicode decoder for charset.
+  nsCOMPtr<nsIUnicodeDecoder>   mDecoder;
+
+  // Accumulated decoded char buffer.
+  mozilla::Vector<char16_t>     mBuffer;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif //mozilla_dom_ScriptLoader_h
diff --git a/dom/base/nsScriptLoader.cpp b/dom/script/ScriptLoader.cpp
similarity index 73%
rename from dom/base/nsScriptLoader.cpp
rename to dom/script/ScriptLoader.cpp
index 25482fe7b..adc046b7c 100644
--- a/dom/base/nsScriptLoader.cpp
+++ b/dom/script/ScriptLoader.cpp
@@ -4,11 +4,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/*
- * A class that handles loading and evaluation of <script> elements.
- */
-
-#include "nsScriptLoader.h"
+#include "ScriptLoader.h"
+#include "ScriptLoadHandler.h"
+#include "ModuleLoadRequest.h"
+#include "ModuleScript.h"
 
 #include "prsystem.h"
 #include "jsapi.h"
@@ -58,19 +57,19 @@
 #include "mozilla/Unused.h"
 #include "nsIScriptError.h"
 
-using namespace mozilla;
-using namespace mozilla::dom;
-
 using JS::SourceBufferHolder;
 
+namespace mozilla {
+namespace dom {
+
 static LazyLogModule gCspPRLog("CSP");
 
 void
-ImplCycleCollectionUnlink(nsScriptLoadRequestList& aField);
+ImplCycleCollectionUnlink(ScriptLoadRequestList& aField);
 
 void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
-                            nsScriptLoadRequestList& aField,
+                            ScriptLoadRequestList& aField,
                             const char* aName,
                             uint32_t aFlags = 0);
 
@@ -78,23 +77,23 @@ ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
 // nsScriptLoadRequest
 //////////////////////////////////////////////////////////////
 
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsScriptLoadRequest)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ScriptLoadRequest)
 NS_INTERFACE_MAP_END
 
-NS_IMPL_CYCLE_COLLECTING_ADDREF(nsScriptLoadRequest)
-NS_IMPL_CYCLE_COLLECTING_RELEASE(nsScriptLoadRequest)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ScriptLoadRequest)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ScriptLoadRequest)
 
-NS_IMPL_CYCLE_COLLECTION_CLASS(nsScriptLoadRequest)
+NS_IMPL_CYCLE_COLLECTION_CLASS(ScriptLoadRequest)
 
-NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsScriptLoadRequest)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(ScriptLoadRequest)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mElement)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsScriptLoadRequest)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(ScriptLoadRequest)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mElement)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
-nsScriptLoadRequest::~nsScriptLoadRequest()
+ScriptLoadRequest::~ScriptLoadRequest()
 {
   js_free(mScriptTextBuf);
 
@@ -107,21 +106,21 @@ nsScriptLoadRequest::~nsScriptLoadRequest()
 }
 
 void
-nsScriptLoadRequest::SetReady()
+ScriptLoadRequest::SetReady()
 {
   MOZ_ASSERT(mProgress != Progress::Ready);
   mProgress = Progress::Ready;
 }
 
 void
-nsScriptLoadRequest::Cancel()
+ScriptLoadRequest::Cancel()
 {
   MaybeCancelOffThreadScript();
   mIsCanceled = true;
 }
 
 void
-nsScriptLoadRequest::MaybeCancelOffThreadScript()
+ScriptLoadRequest::MaybeCancelOffThreadScript()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
@@ -134,306 +133,28 @@ nsScriptLoadRequest::MaybeCancelOffThreadScript()
   mOffThreadToken = nullptr;
 }
 
-//////////////////////////////////////////////////////////////
-// nsModuleLoadRequest
-//////////////////////////////////////////////////////////////
-
-// A load request for a module, created for every top level module script and
-// every module import.  Load request can share an nsModuleScript if there are
-// multiple imports of the same module.
-
-class nsModuleLoadRequest final : public nsScriptLoadRequest
-{
-  ~nsModuleLoadRequest() {}
-
-  nsModuleLoadRequest(const nsModuleLoadRequest& aOther) = delete;
-  nsModuleLoadRequest(nsModuleLoadRequest&& aOther) = delete;
-
-public:
-  NS_DECL_ISUPPORTS_INHERITED
-  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(nsModuleLoadRequest, nsScriptLoadRequest)
-
-  nsModuleLoadRequest(nsIScriptElement* aElement,
-                      uint32_t aVersion,
-                      CORSMode aCORSMode,
-                      const SRIMetadata& aIntegrity,
-                      nsScriptLoader* aLoader);
-
-  bool IsTopLevel() const {
-    return mIsTopLevel;
-  }
-
-  void SetReady() override;
-  void Cancel() override;
-
-  void ModuleLoaded();
-  void DependenciesLoaded();
-  void LoadFailed();
-
-  // Is this a request for a top level module script or an import?
-  bool mIsTopLevel;
-
-  // The base URL used for resolving relative module imports.
-  nsCOMPtr<nsIURI> mBaseURL;
-
-  // Pointer to the script loader, used to trigger actions when the module load
-  // finishes.
-  RefPtr<nsScriptLoader> mLoader;
-
-  // The importing module, or nullptr for top level module scripts.  Used to
-  // implement the ancestor list checked when fetching module dependencies.
-  RefPtr<nsModuleLoadRequest> mParent;
-
-  // Set to a module script object after a successful load or nullptr on
-  // failure.
-  RefPtr<nsModuleScript> mModuleScript;
-
-  // A promise that is completed on successful load of this module and all of
-  // its dependencies, indicating that the module is ready for instantiation and
-  // evaluation.
-  MozPromiseHolder<GenericPromise> mReady;
-
-  // Array of imported modules.
-  nsTArray<RefPtr<nsModuleLoadRequest>> mImports;
-};
-
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(nsModuleLoadRequest)
-NS_INTERFACE_MAP_END_INHERITING(nsScriptLoadRequest)
-
-NS_IMPL_CYCLE_COLLECTION_INHERITED(nsModuleLoadRequest, nsScriptLoadRequest,
-                                   mBaseURL,
-                                   mLoader,
-                                   mParent,
-                                   mModuleScript,
-                                   mImports)
-
-NS_IMPL_ADDREF_INHERITED(nsModuleLoadRequest, nsScriptLoadRequest)
-NS_IMPL_RELEASE_INHERITED(nsModuleLoadRequest, nsScriptLoadRequest)
-
-nsModuleLoadRequest::nsModuleLoadRequest(nsIScriptElement* aElement,
-                                         uint32_t aVersion,
-                                         CORSMode aCORSMode,
-                                         const SRIMetadata &aIntegrity,
-                                         nsScriptLoader* aLoader)
-  : nsScriptLoadRequest(nsScriptKind::Module,
-                        aElement,
-                        aVersion,
-                        aCORSMode,
-                        aIntegrity),
-    mIsTopLevel(true),
-    mLoader(aLoader)
-{}
-
-inline nsModuleLoadRequest*
-nsScriptLoadRequest::AsModuleRequest()
+inline ModuleLoadRequest*
+ScriptLoadRequest::AsModuleRequest()
 {
   MOZ_ASSERT(IsModuleRequest());
-  return static_cast<nsModuleLoadRequest*>(this);
-}
-
-void nsModuleLoadRequest::Cancel()
-{
-  nsScriptLoadRequest::Cancel();
-  mModuleScript = nullptr;
-  mProgress = nsScriptLoadRequest::Progress::Ready;
-  for (size_t i = 0; i < mImports.Length(); i++) {
-    mImports[i]->Cancel();
-  }
-  mReady.RejectIfExists(NS_ERROR_FAILURE, __func__);
-}
-
-void
-nsModuleLoadRequest::SetReady()
-{
-#ifdef DEBUG
-  for (size_t i = 0; i < mImports.Length(); i++) {
-    MOZ_ASSERT(mImports[i]->IsReadyToRun());
-  }
-#endif
-
-  nsScriptLoadRequest::SetReady();
-  mReady.ResolveIfExists(true, __func__);
-}
-
-void
-nsModuleLoadRequest::ModuleLoaded()
-{
-  // A module that was found to be marked as fetching in the module map has now
-  // been loaded.
-
-  mModuleScript = mLoader->GetFetchedModule(mURI);
-  mLoader->StartFetchingModuleDependencies(this);
-}
-
-void
-nsModuleLoadRequest::DependenciesLoaded()
-{
-  // The module and all of its dependencies have been successfully fetched and
-  // compiled.
-
-  if (!mLoader->InstantiateModuleTree(this)) {
-    LoadFailed();
-    return;
-  }
-
-  SetReady();
-  mLoader->ProcessLoadedModuleTree(this);
-  mLoader = nullptr;
-  mParent = nullptr;
-}
-
-void
-nsModuleLoadRequest::LoadFailed()
-{
-  Cancel();
-  mLoader->ProcessLoadedModuleTree(this);
-  mLoader = nullptr;
-  mParent = nullptr;
-}
-
-//////////////////////////////////////////////////////////////
-// nsModuleScript
-//////////////////////////////////////////////////////////////
-
-// A single module script.  May be used to satisfy multiple load requests.
-
-class nsModuleScript final : public nsISupports
-{
-  enum InstantiationState {
-    Uninstantiated,
-    Instantiated,
-    Errored
-  };
-
-  RefPtr<nsScriptLoader> mLoader;
-  nsCOMPtr<nsIURI> mBaseURL;
-  JS::Heap<JSObject*> mModuleRecord;
-  JS::Heap<JS::Value> mException;
-  InstantiationState mInstantiationState;
-
-  ~nsModuleScript();
-
-public:
-  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
-  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(nsModuleScript)
-
-  nsModuleScript(nsScriptLoader* aLoader,
-                 nsIURI* aBaseURL,
-                 JS::Handle<JSObject*> aModuleRecord);
-
-  nsScriptLoader* Loader() const { return mLoader; }
-  JSObject* ModuleRecord() const { return mModuleRecord; }
-  JS::Value Exception() const { return mException; }
-  nsIURI* BaseURL() const { return mBaseURL; }
-
-  void SetInstantiationResult(JS::Handle<JS::Value> aMaybeException);
-  bool IsUninstantiated() const {
-    return mInstantiationState == Uninstantiated;
-  }
-  bool IsInstantiated() const {
-    return mInstantiationState == Instantiated;
-  }
-  bool InstantiationFailed() const {
-    return mInstantiationState == Errored;
-  }
-
-  void UnlinkModuleRecord();
-};
-
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsModuleScript)
-NS_INTERFACE_MAP_END
-
-NS_IMPL_CYCLE_COLLECTION_CLASS(nsModuleScript)
-
-NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsModuleScript)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mLoader)
-  NS_IMPL_CYCLE_COLLECTION_UNLINK(mBaseURL)
-  tmp->UnlinkModuleRecord();
-NS_IMPL_CYCLE_COLLECTION_UNLINK_END
-
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsModuleScript)
-  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mLoader)
-NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
-
-NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(nsModuleScript)
-  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mModuleRecord)
-  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mException)
-NS_IMPL_CYCLE_COLLECTION_TRACE_END
-
-NS_IMPL_CYCLE_COLLECTING_ADDREF(nsModuleScript)
-NS_IMPL_CYCLE_COLLECTING_RELEASE(nsModuleScript)
-
-nsModuleScript::nsModuleScript(nsScriptLoader *aLoader, nsIURI* aBaseURL,
-                               JS::Handle<JSObject*> aModuleRecord)
- : mLoader(aLoader),
-   mBaseURL(aBaseURL),
-   mModuleRecord(aModuleRecord),
-   mInstantiationState(Uninstantiated)
-{
-  MOZ_ASSERT(mLoader);
-  MOZ_ASSERT(mBaseURL);
-  MOZ_ASSERT(mModuleRecord);
-  MOZ_ASSERT(mException.isUndefined());
-
-  // Make module's host defined field point to this module script object.
-  // This is cleared in the UnlinkModuleRecord().
-  JS::SetModuleHostDefinedField(mModuleRecord, JS::PrivateValue(this));
-  HoldJSObjects(this);
-}
-
-void
-nsModuleScript::UnlinkModuleRecord()
-{
-  // Remove module's back reference to this object request if present.
-  if (mModuleRecord) {
-    MOZ_ASSERT(JS::GetModuleHostDefinedField(mModuleRecord).toPrivate() ==
-               this);
-    JS::SetModuleHostDefinedField(mModuleRecord, JS::UndefinedValue());
-  }
-  mModuleRecord = nullptr;
-  mException.setUndefined();
-}
-
-nsModuleScript::~nsModuleScript()
-{
-  if (mModuleRecord) {
-    // The object may be destroyed without being unlinked first.
-    UnlinkModuleRecord();
-  }
-  DropJSObjects(this);
-}
-
-void
-nsModuleScript::SetInstantiationResult(JS::Handle<JS::Value> aMaybeException)
-{
-  MOZ_ASSERT(mInstantiationState == Uninstantiated);
-  MOZ_ASSERT(mModuleRecord);
-  MOZ_ASSERT(mException.isUndefined());
-
-  if (aMaybeException.isUndefined()) {
-    mInstantiationState = Instantiated;
-  } else {
-    mModuleRecord = nullptr;
-    mException = aMaybeException;
-    mInstantiationState = Errored;
-  }
+  return static_cast<ModuleLoadRequest*>(this);
 }
 
 //////////////////////////////////////////////////////////////
 
-// nsScriptLoadRequestList
+// ScriptLoadRequestList
 //////////////////////////////////////////////////////////////
 
-nsScriptLoadRequestList::~nsScriptLoadRequestList()
+ScriptLoadRequestList::~ScriptLoadRequestList()
 {
   Clear();
 }
 
 void
-nsScriptLoadRequestList::Clear()
+ScriptLoadRequestList::Clear()
 {
   while (!isEmpty()) {
-    RefPtr<nsScriptLoadRequest> first = StealFirst();
+    RefPtr<ScriptLoadRequest> first = StealFirst();
     first->Cancel();
     // And just let it go out of scope and die.
   }
@@ -441,9 +162,9 @@ nsScriptLoadRequestList::Clear()
 
 #ifdef DEBUG
 bool
-nsScriptLoadRequestList::Contains(nsScriptLoadRequest* aElem) const
+ScriptLoadRequestList::Contains(ScriptLoadRequest* aElem) const
 {
-  for (const nsScriptLoadRequest* req = getFirst();
+  for (const ScriptLoadRequest* req = getFirst();
        req; req = req->getNext()) {
     if (req == aElem) {
       return true;
@@ -455,20 +176,20 @@ nsScriptLoadRequestList::Contains(nsScriptLoadRequest* aElem) const
 #endif // DEBUG
 
 inline void
-ImplCycleCollectionUnlink(nsScriptLoadRequestList& aField)
+ImplCycleCollectionUnlink(ScriptLoadRequestList& aField)
 {
   while (!aField.isEmpty()) {
-    RefPtr<nsScriptLoadRequest> first = aField.StealFirst();
+    RefPtr<ScriptLoadRequest> first = aField.StealFirst();
   }
 }
 
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
-                            nsScriptLoadRequestList& aField,
+                            ScriptLoadRequestList& aField,
                             const char* aName,
                             uint32_t aFlags)
 {
-  for (nsScriptLoadRequest* request = aField.getFirst();
+  for (ScriptLoadRequest* request = aField.getFirst();
        request; request = request->getNext())
   {
     CycleCollectionNoteChild(aCallback, request, aName, aFlags);
@@ -476,18 +197,18 @@ ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
 }
 
 //////////////////////////////////////////////////////////////
-// nsScriptLoader::PreloadInfo
+// ScriptLoader::PreloadInfo
 //////////////////////////////////////////////////////////////
 
 inline void
-ImplCycleCollectionUnlink(nsScriptLoader::PreloadInfo& aField)
+ImplCycleCollectionUnlink(ScriptLoader::PreloadInfo& aField)
 {
   ImplCycleCollectionUnlink(aField.mRequest);
 }
 
 inline void
 ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
-                            nsScriptLoader::PreloadInfo& aField,
+                            ScriptLoader::PreloadInfo& aField,
                             const char* aName,
                             uint32_t aFlags = 0)
 {
@@ -495,13 +216,13 @@ ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
 }
 
 //////////////////////////////////////////////////////////////
-// nsScriptLoader
+// ScriptLoader
 //////////////////////////////////////////////////////////////
 
-NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(nsScriptLoader)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(ScriptLoader)
 NS_INTERFACE_MAP_END
 
-NS_IMPL_CYCLE_COLLECTION(nsScriptLoader,
+NS_IMPL_CYCLE_COLLECTION(ScriptLoader,
                          mNonAsyncExternalScriptInsertedRequests,
                          mLoadingAsyncRequests,
                          mLoadedAsyncRequests,
@@ -512,10 +233,10 @@ NS_IMPL_CYCLE_COLLECTION(nsScriptLoader,
                          mPendingChildLoaders,
                          mFetchedModules)
 
-NS_IMPL_CYCLE_COLLECTING_ADDREF(nsScriptLoader)
-NS_IMPL_CYCLE_COLLECTING_RELEASE(nsScriptLoader)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(ScriptLoader)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(ScriptLoader)
 
-nsScriptLoader::nsScriptLoader(nsIDocument *aDocument)
+ScriptLoader::ScriptLoader(nsIDocument *aDocument)
   : mDocument(aDocument),
     mParserBlockingBlockerCount(0),
     mBlockerCount(0),
@@ -528,7 +249,7 @@ nsScriptLoader::nsScriptLoader(nsIDocument *aDocument)
 {
 }
 
-nsScriptLoader::~nsScriptLoader()
+ScriptLoader::~ScriptLoader()
 {
   mObservers.Clear();
 
@@ -536,27 +257,27 @@ nsScriptLoader::~nsScriptLoader()
     mParserBlockingRequest->FireScriptAvailable(NS_ERROR_ABORT);
   }
 
-  for (nsScriptLoadRequest* req = mXSLTRequests.getFirst(); req;
+  for (ScriptLoadRequest* req = mXSLTRequests.getFirst(); req;
        req = req->getNext()) {
     req->FireScriptAvailable(NS_ERROR_ABORT);
   }
 
-  for (nsScriptLoadRequest* req = mDeferRequests.getFirst(); req;
+  for (ScriptLoadRequest* req = mDeferRequests.getFirst(); req;
        req = req->getNext()) {
     req->FireScriptAvailable(NS_ERROR_ABORT);
   }
 
-  for (nsScriptLoadRequest* req = mLoadingAsyncRequests.getFirst(); req;
+  for (ScriptLoadRequest* req = mLoadingAsyncRequests.getFirst(); req;
        req = req->getNext()) {
     req->FireScriptAvailable(NS_ERROR_ABORT);
   }
 
-  for (nsScriptLoadRequest* req = mLoadedAsyncRequests.getFirst(); req;
+  for (ScriptLoadRequest* req = mLoadedAsyncRequests.getFirst(); req;
        req = req->getNext()) {
     req->FireScriptAvailable(NS_ERROR_ABORT);
   }
 
-  for(nsScriptLoadRequest* req = mNonAsyncExternalScriptInsertedRequests.getFirst();
+  for(ScriptLoadRequest* req = mNonAsyncExternalScriptInsertedRequests.getFirst();
       req;
       req = req->getNext()) {
     req->FireScriptAvailable(NS_ERROR_ABORT);
@@ -623,11 +344,11 @@ IsScriptEventHandler(nsIContent* aScriptElement)
 }
 
 nsresult
-nsScriptLoader::CheckContentPolicy(nsIDocument* aDocument,
-                                   nsISupports *aContext,
-                                   nsIURI *aURI,
-                                   const nsAString &aType,
-                                   bool aIsPreLoad)
+ScriptLoader::CheckContentPolicy(nsIDocument* aDocument,
+                                 nsISupports *aContext,
+                                 nsIURI *aURI,
+                                 const nsAString &aType,
+                                 bool aIsPreLoad)
 {
   nsContentPolicyType contentPolicyType = aIsPreLoad
                                           ? nsIContentPolicy::TYPE_INTERNAL_SCRIPT_PRELOAD
@@ -654,7 +375,7 @@ nsScriptLoader::CheckContentPolicy(nsIDocument* aDocument,
 }
 
 bool
-nsScriptLoader::ModuleScriptsEnabled()
+ScriptLoader::ModuleScriptsEnabled()
 {
   static bool sEnabledForContent = false;
   static bool sCachedPref = false;
@@ -667,7 +388,7 @@ nsScriptLoader::ModuleScriptsEnabled()
 }
 
 bool
-nsScriptLoader::ModuleMapContainsModule(nsModuleLoadRequest *aRequest) const
+ScriptLoader::ModuleMapContainsModule(ModuleLoadRequest *aRequest) const
 {
   // Returns whether we have fetched, or are currently fetching, a module script
   // for the request's URL.
@@ -676,7 +397,7 @@ nsScriptLoader::ModuleMapContainsModule(nsModuleLoadRequest *aRequest) const
 }
 
 bool
-nsScriptLoader::IsFetchingModule(nsModuleLoadRequest *aRequest) const
+ScriptLoader::IsFetchingModule(ModuleLoadRequest *aRequest) const
 {
   bool fetching = mFetchingModules.Contains(aRequest->mURI);
   MOZ_ASSERT_IF(fetching, !mFetchedModules.Contains(aRequest->mURI));
@@ -684,7 +405,7 @@ nsScriptLoader::IsFetchingModule(nsModuleLoadRequest *aRequest) const
 }
 
 void
-nsScriptLoader::SetModuleFetchStarted(nsModuleLoadRequest *aRequest)
+ScriptLoader::SetModuleFetchStarted(ModuleLoadRequest *aRequest)
 {
   // Update the module map to indicate that a module is currently being fetched.
 
@@ -694,8 +415,8 @@ nsScriptLoader::SetModuleFetchStarted(nsModuleLoadRequest *aRequest)
 }
 
 void
-nsScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(nsModuleLoadRequest *aRequest,
-                                                               nsresult aResult)
+ScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(ModuleLoadRequest *aRequest,
+                                                             nsresult aResult)
 {
   // Update module map with the result of fetching a single module script.  The
   // module script pointer is nullptr on error.
@@ -706,7 +427,7 @@ nsScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(nsModuleLoadReque
   MOZ_ALWAYS_TRUE(mFetchingModules.Get(aRequest->mURI, getter_AddRefs(promise)));
   mFetchingModules.Remove(aRequest->mURI);
 
-  RefPtr<nsModuleScript> ms(aRequest->mModuleScript);
+  RefPtr<ModuleScript> ms(aRequest->mModuleScript);
   MOZ_ASSERT(NS_SUCCEEDED(aResult) == (ms != nullptr));
   mFetchedModules.Put(aRequest->mURI, ms);
 
@@ -720,7 +441,7 @@ nsScriptLoader::SetModuleFetchFinishedAndResumeWaitingRequests(nsModuleLoadReque
 }
 
 RefPtr<GenericPromise>
-nsScriptLoader::WaitForModuleFetch(nsModuleLoadRequest *aRequest)
+ScriptLoader::WaitForModuleFetch(ModuleLoadRequest *aRequest)
 {
   MOZ_ASSERT(ModuleMapContainsModule(aRequest));
 
@@ -733,7 +454,7 @@ nsScriptLoader::WaitForModuleFetch(nsModuleLoadRequest *aRequest)
     return promise;
   }
 
-  RefPtr<nsModuleScript> ms;
+  RefPtr<ModuleScript> ms;
   MOZ_ALWAYS_TRUE(mFetchedModules.Get(aRequest->mURI, getter_AddRefs(ms)));
   if (!ms) {
     return GenericPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
@@ -742,17 +463,17 @@ nsScriptLoader::WaitForModuleFetch(nsModuleLoadRequest *aRequest)
   return GenericPromise::CreateAndResolve(true, __func__);
 }
 
-nsModuleScript*
-nsScriptLoader::GetFetchedModule(nsIURI* aURL) const
+ModuleScript*
+ScriptLoader::GetFetchedModule(nsIURI* aURL) const
 {
   bool found;
-  nsModuleScript* ms = mFetchedModules.GetWeak(aURL, &found);
+  ModuleScript* ms = mFetchedModules.GetWeak(aURL, &found);
   MOZ_ASSERT(found);
   return ms;
 }
 
 nsresult
-nsScriptLoader::ProcessFetchedModuleSource(nsModuleLoadRequest* aRequest)
+ScriptLoader::ProcessFetchedModuleSource(ModuleLoadRequest* aRequest)
 {
   MOZ_ASSERT(!aRequest->mModuleScript);
 
@@ -771,7 +492,7 @@ nsScriptLoader::ProcessFetchedModuleSource(nsModuleLoadRequest* aRequest)
 }
 
 nsresult
-nsScriptLoader::CreateModuleScript(nsModuleLoadRequest* aRequest)
+ScriptLoader::CreateModuleScript(ModuleLoadRequest* aRequest)
 {
   MOZ_ASSERT(!aRequest->mModuleScript);
   MOZ_ASSERT(aRequest->mBaseURL);
@@ -825,7 +546,7 @@ nsScriptLoader::CreateModuleScript(nsModuleLoadRequest* aRequest)
     MOZ_ASSERT(NS_SUCCEEDED(rv) == (module != nullptr));
     if (module) {
       aRequest->mModuleScript =
-        new nsModuleScript(this, aRequest->mBaseURL, module);
+        new ModuleScript(this, aRequest->mBaseURL, module);
     }
   }
 
@@ -835,7 +556,7 @@ nsScriptLoader::CreateModuleScript(nsModuleLoadRequest* aRequest)
 }
 
 static bool
-ThrowTypeError(JSContext* aCx, nsModuleScript* aScript,
+ThrowTypeError(JSContext* aCx, ModuleScript* aScript,
                const nsString& aMessage)
 {
   JS::Rooted<JSObject*> module(aCx, aScript->ModuleRecord());
@@ -862,7 +583,7 @@ ThrowTypeError(JSContext* aCx, nsModuleScript* aScript,
 }
 
 static bool
-HandleResolveFailure(JSContext* aCx, nsModuleScript* aScript,
+HandleResolveFailure(JSContext* aCx, ModuleScript* aScript,
                      const nsAString& aSpecifier)
 {
   // TODO: How can we get the line number of the failed import?
@@ -874,7 +595,7 @@ HandleResolveFailure(JSContext* aCx, nsModuleScript* aScript,
 }
 
 static bool
-HandleModuleNotFound(JSContext* aCx, nsModuleScript* aScript,
+HandleModuleNotFound(JSContext* aCx, ModuleScript* aScript,
                      const nsAString& aSpecifier)
 {
   // TODO: How can we get the line number of the failed import?
@@ -886,7 +607,7 @@ HandleModuleNotFound(JSContext* aCx, nsModuleScript* aScript,
 }
 
 static already_AddRefed<nsIURI>
-ResolveModuleSpecifier(nsModuleScript* aScript,
+ResolveModuleSpecifier(ModuleScript* aScript,
                        const nsAString& aSpecifier)
 {
   // The following module specifiers are allowed by the spec:
@@ -921,7 +642,7 @@ ResolveModuleSpecifier(nsModuleScript* aScript,
 }
 
 static nsresult
-RequestedModuleIsInAncestorList(nsModuleLoadRequest* aRequest, nsIURI* aURL, bool* aResult)
+RequestedModuleIsInAncestorList(ModuleLoadRequest* aRequest, nsIURI* aURL, bool* aResult)
 {
   const size_t ImportDepthLimit = 100;
 
@@ -947,9 +668,9 @@ RequestedModuleIsInAncestorList(nsModuleLoadRequest* aRequest, nsIURI* aURL, boo
 }
 
 static nsresult
-ResolveRequestedModules(nsModuleLoadRequest* aRequest, nsCOMArray<nsIURI> &aUrls)
+ResolveRequestedModules(ModuleLoadRequest* aRequest, nsCOMArray<nsIURI> &aUrls)
 {
-  nsModuleScript* ms = aRequest->mModuleScript;
+  ModuleScript* ms = aRequest->mModuleScript;
 
   AutoJSAPI jsapi;
   if (!jsapi.Init(ms->ModuleRecord())) {
@@ -977,7 +698,7 @@ ResolveRequestedModules(nsModuleLoadRequest* aRequest, nsCOMArray<nsIURI> &aUrls
     }
 
     // Let url be the result of resolving a module specifier given module script and requested.
-    nsModuleScript* ms = aRequest->mModuleScript;
+    ModuleScript* ms = aRequest->mModuleScript;
     nsCOMPtr<nsIURI> uri = ResolveModuleSpecifier(ms, specifier);
     if (!uri) {
       HandleResolveFailure(cx, ms, specifier);
@@ -996,11 +717,11 @@ ResolveRequestedModules(nsModuleLoadRequest* aRequest, nsCOMArray<nsIURI> &aUrls
 }
 
 void
-nsScriptLoader::StartFetchingModuleDependencies(nsModuleLoadRequest* aRequest)
+ScriptLoader::StartFetchingModuleDependencies(ModuleLoadRequest* aRequest)
 {
   MOZ_ASSERT(aRequest->mModuleScript);
   MOZ_ASSERT(!aRequest->IsReadyToRun());
-  aRequest->mProgress = nsModuleLoadRequest::Progress::FetchingImports;
+  aRequest->mProgress = ModuleLoadRequest::Progress::FetchingImports;
 
   nsCOMArray<nsIURI> urls;
   nsresult rv = ResolveRequestedModules(aRequest, urls);
@@ -1028,19 +749,19 @@ nsScriptLoader::StartFetchingModuleDependencies(nsModuleLoadRequest* aRequest)
   RefPtr<GenericPromise::AllPromiseType> allReady =
     GenericPromise::All(AbstractThread::GetCurrent(), importsReady);
   allReady->Then(AbstractThread::GetCurrent(), __func__, aRequest,
-                 &nsModuleLoadRequest::DependenciesLoaded,
-                 &nsModuleLoadRequest::LoadFailed);
+                 &ModuleLoadRequest::DependenciesLoaded,
+                 &ModuleLoadRequest::LoadFailed);
 }
 
 RefPtr<GenericPromise>
-nsScriptLoader::StartFetchingModuleAndDependencies(nsModuleLoadRequest* aRequest,
-                                                   nsIURI* aURI)
+ScriptLoader::StartFetchingModuleAndDependencies(ModuleLoadRequest* aRequest,
+                                                 nsIURI* aURI)
 {
   MOZ_ASSERT(aURI);
 
-  RefPtr<nsModuleLoadRequest> childRequest =
-    new nsModuleLoadRequest(aRequest->mElement, aRequest->mJSVersion,
-                            aRequest->mCORSMode, aRequest->mIntegrity, this);
+  RefPtr<ModuleLoadRequest> childRequest =
+    new ModuleLoadRequest(aRequest->mElement, aRequest->mJSVersion,
+                          aRequest->mCORSMode, aRequest->mIntegrity, this);
 
   childRequest->mIsTopLevel = false;
   childRequest->mURI = aURI;
@@ -1070,7 +791,7 @@ HostResolveImportedModule(JSContext* aCx, unsigned argc, JS::Value* vp)
 
   // Let referencing module script be referencingModule.[[HostDefined]].
   JS::Value value = JS::GetModuleHostDefinedField(module);
-  auto script = static_cast<nsModuleScript*>(value.toPrivate());
+  auto script = static_cast<ModuleScript*>(value.toPrivate());
   MOZ_ASSERT(script->ModuleRecord() == module);
 
   // Let url be the result of resolving a module specifier given referencing
@@ -1089,7 +810,7 @@ HostResolveImportedModule(JSContext* aCx, unsigned argc, JS::Value* vp)
   // Let resolved module script be the value of the entry in module map whose
   // key is url. If no such entry exists, throw a TypeError exception and abort
   // these steps.
-  nsModuleScript* ms = script->Loader()->GetFetchedModule(uri);
+  ModuleScript* ms = script->Loader()->GetFetchedModule(uri);
   if (!ms) {
     return HandleModuleNotFound(aCx, script, string);
   }
@@ -1123,7 +844,7 @@ EnsureModuleResolveHook(JSContext* aCx)
 }
 
 void
-nsScriptLoader::ProcessLoadedModuleTree(nsModuleLoadRequest* aRequest)
+ScriptLoader::ProcessLoadedModuleTree(ModuleLoadRequest* aRequest)
 {
   if (aRequest->IsTopLevel()) {
     MaybeMoveToLoadedList(aRequest);
@@ -1136,13 +857,13 @@ nsScriptLoader::ProcessLoadedModuleTree(nsModuleLoadRequest* aRequest)
 }
 
 bool
-nsScriptLoader::InstantiateModuleTree(nsModuleLoadRequest* aRequest)
+ScriptLoader::InstantiateModuleTree(ModuleLoadRequest* aRequest)
 {
   // Perform eager instantiation of the loaded module tree.
 
   MOZ_ASSERT(aRequest);
 
-  nsModuleScript* ms = aRequest->mModuleScript;
+  ModuleScript* ms = aRequest->mModuleScript;
   MOZ_ASSERT(ms);
   if (!ms || !ms->ModuleRecord()) {
     return false;
@@ -1171,14 +892,14 @@ nsScriptLoader::InstantiateModuleTree(nsModuleLoadRequest* aRequest)
   // Mark this module and any uninstantiated dependencies found via depth-first
   // search as instantiated and record any error.
 
-  mozilla::Vector<nsModuleLoadRequest*, 1> requests;
+  mozilla::Vector<ModuleLoadRequest*, 1> requests;
   if (!requests.append(aRequest)) {
     return false;
   }
 
   while (!requests.empty()) {
-    nsModuleLoadRequest* request = requests.popCopy();
-    nsModuleScript* ms = request->mModuleScript;
+    ModuleLoadRequest* request = requests.popCopy();
+    ModuleScript* ms = request->mModuleScript;
     if (!ms->IsUninstantiated()) {
       continue;
     }
@@ -1198,8 +919,8 @@ nsScriptLoader::InstantiateModuleTree(nsModuleLoadRequest* aRequest)
 }
 
 nsresult
-nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
-                          bool aScriptFromHead)
+ScriptLoader::StartLoad(ScriptLoadRequest *aRequest, const nsAString &aType,
+                        bool aScriptFromHead)
 {
   MOZ_ASSERT(aRequest->IsLoading());
   NS_ENSURE_TRUE(mDocument, NS_ERROR_NULL_POINTER);
@@ -1212,12 +933,12 @@ nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
   if (aRequest->IsModuleRequest()) {
     // Check whether the module has been fetched or is currently being fetched,
     // and if so wait for it.
-    nsModuleLoadRequest* request = aRequest->AsModuleRequest();
+    ModuleLoadRequest* request = aRequest->AsModuleRequest();
     if (ModuleMapContainsModule(request)) {
       WaitForModuleFetch(request)
         ->Then(AbstractThread::GetCurrent(), __func__, request,
-               &nsModuleLoadRequest::ModuleLoaded,
-               &nsModuleLoadRequest::LoadFailed);
+               &ModuleLoadRequest::ModuleLoaded,
+               &ModuleLoadRequest::LoadFailed);
       return NS_OK;
     }
 
@@ -1330,8 +1051,8 @@ nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
                                                mReporter);
   }
 
-  RefPtr<nsScriptLoadHandler> handler =
-      new nsScriptLoadHandler(this, aRequest, sriDataVerifier.forget());
+  RefPtr<ScriptLoadHandler> handler =
+      new ScriptLoadHandler(this, aRequest, sriDataVerifier.forget());
 
   nsCOMPtr<nsIIncrementalStreamLoader> loader;
   rv = NS_NewIncrementalStreamLoader(getter_AddRefs(loader), handler);
@@ -1341,22 +1062,22 @@ nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
 }
 
 bool
-nsScriptLoader::PreloadURIComparator::Equals(const PreloadInfo &aPi,
-                                             nsIURI * const &aURI) const
+ScriptLoader::PreloadURIComparator::Equals(const PreloadInfo &aPi,
+                                           nsIURI * const &aURI) const
 {
   bool same;
   return NS_SUCCEEDED(aPi.mRequest->mURI->Equals(aURI, &same)) &&
          same;
 }
 
-class nsScriptRequestProcessor : public Runnable
+class ScriptRequestProcessor : public Runnable
 {
 private:
-  RefPtr<nsScriptLoader> mLoader;
-  RefPtr<nsScriptLoadRequest> mRequest;
+  RefPtr<ScriptLoader> mLoader;
+  RefPtr<ScriptLoadRequest> mRequest;
 public:
-  nsScriptRequestProcessor(nsScriptLoader* aLoader,
-                           nsScriptLoadRequest* aRequest)
+  ScriptRequestProcessor(ScriptLoader* aLoader,
+                         ScriptLoadRequest* aRequest)
     : mLoader(aLoader)
     , mRequest(aRequest)
   {}
@@ -1428,24 +1149,23 @@ CSPAllowsInlineScript(nsIScriptElement *aElement, nsIDocument *aDocument)
   return allowInlineScript;
 }
 
-nsScriptLoadRequest*
-nsScriptLoader::CreateLoadRequest(nsScriptKind aKind,
-                                  nsIScriptElement* aElement,
-                                  uint32_t aVersion, CORSMode aCORSMode,
-                                  const SRIMetadata &aIntegrity)
+ScriptLoadRequest*
+ScriptLoader::CreateLoadRequest(ScriptKind aKind,
+                                nsIScriptElement* aElement,
+                                uint32_t aVersion, CORSMode aCORSMode,
+                                const SRIMetadata &aIntegrity)
 {
-  if (aKind == nsScriptKind::Classic) {
-    return new nsScriptLoadRequest(aKind, aElement, aVersion, aCORSMode,
-                                   aIntegrity);
+  if (aKind == ScriptKind::Classic) {
+    return new ScriptLoadRequest(aKind, aElement, aVersion, aCORSMode,
+                                 aIntegrity);
   }
 
-  MOZ_ASSERT(aKind == nsScriptKind::Module);
-  return new nsModuleLoadRequest(aElement, aVersion, aCORSMode, aIntegrity,
-                                 this);
+  MOZ_ASSERT(aKind == ScriptKind::Module);
+  return new ModuleLoadRequest(aElement, aVersion, aCORSMode, aIntegrity, this);
 }
 
 bool
-nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
+ScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
 {
   // We need a document to evaluate scripts.
   NS_ENSURE_TRUE(mDocument, false);
@@ -1471,10 +1191,10 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   nsAutoString type;
   bool hasType = aElement->GetScriptType(type);
 
-  nsScriptKind scriptKind = nsScriptKind::Classic;
+  ScriptKind scriptKind = ScriptKind::Classic;
   if (!type.IsEmpty()) {
     if (ModuleScriptsEnabled() && type.LowerCaseEqualsASCII("module")) {
-      scriptKind = nsScriptKind::Module;
+      scriptKind = ScriptKind::Module;
     } else {
       NS_ENSURE_TRUE(ParseTypeAttribute(type, &version), false);
     }
@@ -1498,7 +1218,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   // "The nomodule attribute must not be specified on module scripts (and will
   // be ignored if it is)."
   if (ModuleScriptsEnabled() &&
-      scriptKind == nsScriptKind::Classic &&
+      scriptKind == ScriptKind::Classic &&
       scriptContent->IsHTMLElement() &&
       scriptContent->HasAttr(kNameSpaceID_None, nsGkAtoms::nomodule)) {
     return false;
@@ -1506,7 +1226,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
 
   // Step 15. and later in the HTML5 spec
   nsresult rv = NS_OK;
-  RefPtr<nsScriptLoadRequest> request;
+  RefPtr<ScriptLoadRequest> request;
   if (aElement->GetScriptExternal()) {
     // external script
     nsCOMPtr<nsIURI> scriptURI = aElement->GetScriptURI();
@@ -1562,7 +1282,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
                                integrity);
         if (!integrity.IsEmpty()) {
           MOZ_LOG(SRILogHelper::GetSriLog(), mozilla::LogLevel::Debug,
-                 ("nsScriptLoader::ProcessScriptElement, integrity=%s",
+                 ("ScriptLoader::ProcessScriptElement, integrity=%s",
                   NS_ConvertUTF16toUTF8(integrity).get()));
           nsAutoCString sourceUri;
           if (mDocument->GetDocumentURI()) {
@@ -1704,7 +1424,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   request->mLineNo = aElement->GetScriptLineNumber();
 
   if (request->IsModuleRequest()) {
-    nsModuleLoadRequest* modReq = request->AsModuleRequest();
+    ModuleLoadRequest* modReq = request->AsModuleRequest();
     modReq->mBaseURL = mDocument->GetDocBaseURI();
     rv = CreateModuleScript(modReq);
     NS_ENSURE_SUCCESS(rv, false);
@@ -1716,7 +1436,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
     }
     return false;
   }
-  request->mProgress = nsScriptLoadRequest::Progress::Ready;
+  request->mProgress = ScriptLoadRequest::Progress::Ready;
   if (aElement->GetParserCreated() == FROM_PARSER_XSLT &&
       (!ReadyToExecuteParserBlockingScripts() || !mXSLTRequests.isEmpty())) {
     // Need to maintain order for XSLT-inserted scripts
@@ -1728,7 +1448,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   if (aElement->GetParserCreated() == NOT_FROM_PARSER) {
     NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
         "A script-inserted script is inserted without an update batch?");
-    nsContentUtils::AddScriptRunner(new nsScriptRequestProcessor(this,
+    nsContentUtils::AddScriptRunner(new ScriptRequestProcessor(this,
                                                                  request));
     return false;
   }
@@ -1758,13 +1478,13 @@ namespace {
 
 class NotifyOffThreadScriptLoadCompletedRunnable : public Runnable
 {
-  RefPtr<nsScriptLoadRequest> mRequest;
-  RefPtr<nsScriptLoader> mLoader;
+  RefPtr<ScriptLoadRequest> mRequest;
+  RefPtr<ScriptLoader> mLoader;
   void *mToken;
 
 public:
-  NotifyOffThreadScriptLoadCompletedRunnable(nsScriptLoadRequest* aRequest,
-                                             nsScriptLoader* aLoader)
+  NotifyOffThreadScriptLoadCompletedRunnable(ScriptLoadRequest* aRequest,
+                                             ScriptLoader* aLoader)
     : mRequest(aRequest), mLoader(aLoader), mToken(nullptr)
   {}
 
@@ -1781,16 +1501,16 @@ public:
 } /* anonymous namespace */
 
 nsresult
-nsScriptLoader::ProcessOffThreadRequest(nsScriptLoadRequest* aRequest)
+ScriptLoader::ProcessOffThreadRequest(ScriptLoadRequest* aRequest)
 {
-  MOZ_ASSERT(aRequest->mProgress == nsScriptLoadRequest::Progress::Compiling);
+  MOZ_ASSERT(aRequest->mProgress == ScriptLoadRequest::Progress::Compiling);
   MOZ_ASSERT(!aRequest->mWasCompiledOMT);
 
   aRequest->mWasCompiledOMT = true;
 
   if (aRequest->IsModuleRequest()) {
     MOZ_ASSERT(aRequest->mOffThreadToken);
-    nsModuleLoadRequest* request = aRequest->AsModuleRequest();
+    ModuleLoadRequest* request = aRequest->AsModuleRequest();
     nsresult rv = ProcessFetchedModuleSource(request);
     if (NS_FAILED(rv)) {
       request->LoadFailed();
@@ -1837,8 +1557,8 @@ NotifyOffThreadScriptLoadCompletedRunnable::Run()
 
   // We want these to be dropped on the main thread, once we return from this
   // function.
-  RefPtr<nsScriptLoadRequest> request = mRequest.forget();
-  RefPtr<nsScriptLoader> loader = mLoader.forget();
+  RefPtr<ScriptLoadRequest> request = mRequest.forget();
+  RefPtr<ScriptLoader> loader = mLoader.forget();
 
   request->mOffThreadToken = mToken;
   nsresult rv = loader->ProcessOffThreadRequest(request);
@@ -1856,7 +1576,7 @@ OffThreadScriptLoaderCallback(void *aToken, void *aCallbackData)
 }
 
 nsresult
-nsScriptLoader::AttemptAsyncScriptCompile(nsScriptLoadRequest* aRequest)
+ScriptLoader::AttemptAsyncScriptCompile(ScriptLoadRequest* aRequest)
 {
   MOZ_ASSERT_IF(!aRequest->IsModuleRequest(), aRequest->IsReadyToRun());
   MOZ_ASSERT(!aRequest->mWasCompiledOMT);
@@ -1909,14 +1629,14 @@ nsScriptLoader::AttemptAsyncScriptCompile(nsScriptLoadRequest* aRequest)
   }
 
   mDocument->BlockOnload();
-  aRequest->mProgress = nsScriptLoadRequest::Progress::Compiling;
+  aRequest->mProgress = ScriptLoadRequest::Progress::Compiling;
 
   Unused << runnable.forget();
   return NS_OK;
 }
 
 nsresult
-nsScriptLoader::CompileOffThreadOrProcessRequest(nsScriptLoadRequest* aRequest)
+ScriptLoader::CompileOffThreadOrProcessRequest(ScriptLoadRequest* aRequest)
 {
   NS_ASSERTION(nsContentUtils::IsSafeToRunScript(),
                "Processing requests when running scripts is unsafe.");
@@ -1934,7 +1654,7 @@ nsScriptLoader::CompileOffThreadOrProcessRequest(nsScriptLoadRequest* aRequest)
 }
 
 SourceBufferHolder
-nsScriptLoader::GetScriptSource(nsScriptLoadRequest* aRequest, nsAutoString& inlineData)
+ScriptLoader::GetScriptSource(ScriptLoadRequest* aRequest, nsAutoString& inlineData)
 {
   // Return a SourceBufferHolder object holding the script's source text.
   // |inlineData| is used to hold the text for inline objects.
@@ -1955,7 +1675,7 @@ nsScriptLoader::GetScriptSource(nsScriptLoadRequest* aRequest, nsAutoString& inl
 }
 
 nsresult
-nsScriptLoader::ProcessRequest(nsScriptLoadRequest* aRequest)
+ScriptLoader::ProcessRequest(ScriptLoadRequest* aRequest)
 {
   NS_ASSERTION(nsContentUtils::IsSafeToRunScript(),
                "Processing requests when running scripts is unsafe.");
@@ -2055,8 +1775,8 @@ nsScriptLoader::ProcessRequest(nsScriptLoadRequest* aRequest)
 }
 
 void
-nsScriptLoader::FireScriptAvailable(nsresult aResult,
-                                    nsScriptLoadRequest* aRequest)
+ScriptLoader::FireScriptAvailable(nsresult aResult,
+                                  ScriptLoadRequest* aRequest)
 {
   for (int32_t i = 0; i < mObservers.Count(); i++) {
     nsCOMPtr<nsIScriptLoaderObserver> obs = mObservers[i];
@@ -2069,8 +1789,8 @@ nsScriptLoader::FireScriptAvailable(nsresult aResult,
 }
 
 void
-nsScriptLoader::FireScriptEvaluated(nsresult aResult,
-                                    nsScriptLoadRequest* aRequest)
+ScriptLoader::FireScriptEvaluated(nsresult aResult,
+                                  ScriptLoadRequest* aRequest)
 {
   for (int32_t i = 0; i < mObservers.Count(); i++) {
     nsCOMPtr<nsIScriptLoaderObserver> obs = mObservers[i];
@@ -2082,7 +1802,7 @@ nsScriptLoader::FireScriptEvaluated(nsresult aResult,
 }
 
 already_AddRefed<nsIScriptGlobalObject>
-nsScriptLoader::GetScriptGlobalObject()
+ScriptLoader::GetScriptGlobalObject()
 {
   nsCOMPtr<nsIDocument> master = mDocument->MasterDocument();
   nsPIDOMWindowInner *pwin = master->GetInnerWindow();
@@ -2103,10 +1823,10 @@ nsScriptLoader::GetScriptGlobalObject()
 }
 
 nsresult
-nsScriptLoader::FillCompileOptionsForRequest(const AutoJSAPI&jsapi,
-                                             nsScriptLoadRequest* aRequest,
-                                             JS::Handle<JSObject*> aScopeChain,
-                                             JS::CompileOptions* aOptions)
+ScriptLoader::FillCompileOptionsForRequest(const AutoJSAPI&jsapi,
+                                           ScriptLoadRequest* aRequest,
+                                           JS::Handle<JSObject*> aScopeChain,
+                                           JS::CompileOptions* aOptions)
 {
   // It's very important to use aRequest->mURI, not the final URI of the channel
   // aRequest ended up getting script data from, as the script filename.
@@ -2150,7 +1870,7 @@ nsScriptLoader::FillCompileOptionsForRequest(const AutoJSAPI&jsapi,
 }
 
 nsresult
-nsScriptLoader::EvaluateScript(nsScriptLoadRequest* aRequest)
+ScriptLoader::EvaluateScript(ScriptLoadRequest* aRequest)
 {
   // We need a document to evaluate scripts.
   if (!mDocument) {
@@ -2211,10 +1931,10 @@ nsScriptLoader::EvaluateScript(nsScriptLoadRequest* aRequest)
     }
 
     if (aRequest->IsModuleRequest()) {
-      nsModuleLoadRequest* request = aRequest->AsModuleRequest();
+      ModuleLoadRequest* request = aRequest->AsModuleRequest();
       MOZ_ASSERT(request->mModuleScript);
       MOZ_ASSERT(!request->mOffThreadToken);
-      nsModuleScript* ms = request->mModuleScript;
+      ModuleScript* ms = request->mModuleScript;
       MOZ_ASSERT(!ms->IsUninstantiated());
       if (ms->InstantiationFailed()) {
         JS::Rooted<JS::Value> exception(aes.cx(), ms->Exception());
@@ -2243,7 +1963,7 @@ nsScriptLoader::EvaluateScript(nsScriptLoadRequest* aRequest)
 }
 
 void
-nsScriptLoader::ProcessPendingRequestsAsync()
+ScriptLoader::ProcessPendingRequestsAsync()
 {
   if (mParserBlockingRequest ||
       !mXSLTRequests.isEmpty() ||
@@ -2252,14 +1972,14 @@ nsScriptLoader::ProcessPendingRequestsAsync()
       !mDeferRequests.isEmpty() ||
       !mPendingChildLoaders.IsEmpty()) {
     NS_DispatchToCurrentThread(NewRunnableMethod(this,
-                                                 &nsScriptLoader::ProcessPendingRequests));
+                                                 &ScriptLoader::ProcessPendingRequests));
   }
 }
 
 void
-nsScriptLoader::ProcessPendingRequests()
+ScriptLoader::ProcessPendingRequests()
 {
-  RefPtr<nsScriptLoadRequest> request;
+  RefPtr<ScriptLoadRequest> request;
 
   if (mParserBlockingRequest &&
       mParserBlockingRequest->IsReadyToRun() &&
@@ -2311,7 +2031,7 @@ nsScriptLoader::ProcessPendingRequests()
 
   while (!mPendingChildLoaders.IsEmpty() &&
          ReadyToExecuteParserBlockingScripts()) {
-    RefPtr<nsScriptLoader> child = mPendingChildLoaders[0];
+    RefPtr<ScriptLoader> child = mPendingChildLoaders[0];
     mPendingChildLoaders.RemoveElementAt(0);
     child->RemoveParserBlockingScriptExecutionBlocker();
   }
@@ -2337,7 +2057,7 @@ nsScriptLoader::ProcessPendingRequests()
 }
 
 bool
-nsScriptLoader::ReadyToExecuteParserBlockingScripts()
+ScriptLoader::ReadyToExecuteParserBlockingScripts()
 {
   // Make sure the SelfReadyToExecuteParserBlockingScripts check is first, so
   // that we don't block twice on an ancestor.
@@ -2346,7 +2066,7 @@ nsScriptLoader::ReadyToExecuteParserBlockingScripts()
   }
 
   for (nsIDocument* doc = mDocument; doc; doc = doc->GetParentDocument()) {
-    nsScriptLoader* ancestor = doc->ScriptLoader();
+    ScriptLoader* ancestor = doc->ScriptLoader();
     if (!ancestor->SelfReadyToExecuteParserBlockingScripts() &&
         ancestor->AddPendingChildLoader(this)) {
       AddParserBlockingScriptExecutionBlocker();
@@ -2394,10 +2114,10 @@ nsScriptLoader::ReadyToExecuteParserBlockingScripts()
 }
 
 /* static */ nsresult
-nsScriptLoader::ConvertToUTF16(nsIChannel* aChannel, const uint8_t* aData,
-                               uint32_t aLength, const nsAString& aHintCharset,
-                               nsIDocument* aDocument,
-                               char16_t*& aBufOut, size_t& aLengthOut)
+ScriptLoader::ConvertToUTF16(nsIChannel* aChannel, const uint8_t* aData,
+                             uint32_t aLength, const nsAString& aHintCharset,
+                             nsIDocument* aDocument,
+                             char16_t*& aBufOut, size_t& aLengthOut)
 {
   if (!aLength) {
     aBufOut = nullptr;
@@ -2474,14 +2194,14 @@ nsScriptLoader::ConvertToUTF16(nsIChannel* aChannel, const uint8_t* aData,
 }
 
 nsresult
-nsScriptLoader::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
-                                 nsISupports* aContext,
-                                 nsresult aChannelStatus,
-                                 nsresult aSRIStatus,
-                                 mozilla::Vector<char16_t> &aString,
-                                 mozilla::dom::SRICheckDataVerifier* aSRIDataVerifier)
+ScriptLoader::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
+                               nsISupports* aContext,
+                               nsresult aChannelStatus,
+                               nsresult aSRIStatus,
+                               mozilla::Vector<char16_t> &aString,
+                               mozilla::dom::SRICheckDataVerifier* aSRIDataVerifier)
 {
-  nsScriptLoadRequest* request = static_cast<nsScriptLoadRequest*>(aContext);
+  ScriptLoadRequest* request = static_cast<ScriptLoadRequest*>(aContext);
   NS_ASSERTION(request, "null request in stream complete handler");
   NS_ENSURE_TRUE(request, NS_ERROR_FAILURE);
 
@@ -2511,7 +2231,7 @@ nsScriptLoader::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
 
     if (loadInfo->GetEnforceSRI()) {
       MOZ_LOG(SRILogHelper::GetSriLog(), mozilla::LogLevel::Debug,
-             ("nsScriptLoader::OnStreamComplete, required SRI not found"));
+             ("ScriptLoader::OnStreamComplete, required SRI not found"));
       nsCOMPtr<nsIContentSecurityPolicy> csp;
       loadInfo->LoadingPrincipal()->GetCsp(getter_AddRefs(csp));
       nsAutoCString violationURISpec;
@@ -2544,29 +2264,29 @@ nsScriptLoader::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
       MOZ_ASSERT_IF(request->IsModuleRequest(),
                     request->AsModuleRequest()->IsTopLevel());
       if (request->isInList()) {
-        RefPtr<nsScriptLoadRequest> req = mDeferRequests.Steal(request);
+        RefPtr<ScriptLoadRequest> req = mDeferRequests.Steal(request);
         FireScriptAvailable(rv, req);
       }
     } else if (request->mIsAsync) {
       MOZ_ASSERT_IF(request->IsModuleRequest(),
                     request->AsModuleRequest()->IsTopLevel());
       if (request->isInList()) {
-        RefPtr<nsScriptLoadRequest> req = mLoadingAsyncRequests.Steal(request);
+        RefPtr<ScriptLoadRequest> req = mLoadingAsyncRequests.Steal(request);
         FireScriptAvailable(rv, req);
       }
     } else if (request->mIsNonAsyncScriptInserted) {
       if (request->isInList()) {
-        RefPtr<nsScriptLoadRequest> req =
+        RefPtr<ScriptLoadRequest> req =
           mNonAsyncExternalScriptInsertedRequests.Steal(request);
         FireScriptAvailable(rv, req);
       }
     } else if (request->mIsXSLT) {
       if (request->isInList()) {
-        RefPtr<nsScriptLoadRequest> req = mXSLTRequests.Steal(request);
+        RefPtr<ScriptLoadRequest> req = mXSLTRequests.Steal(request);
         FireScriptAvailable(rv, req);
       }
     } else if (request->IsModuleRequest()) {
-      nsModuleLoadRequest* modReq = request->AsModuleRequest();
+      ModuleLoadRequest* modReq = request->AsModuleRequest();
       MOZ_ASSERT(!modReq->IsTopLevel());
       MOZ_ASSERT(!modReq->isInList());
       modReq->Cancel();
@@ -2597,19 +2317,19 @@ nsScriptLoader::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
 }
 
 void
-nsScriptLoader::UnblockParser(nsScriptLoadRequest* aParserBlockingRequest)
+ScriptLoader::UnblockParser(ScriptLoadRequest* aParserBlockingRequest)
 {
   aParserBlockingRequest->mElement->UnblockParser();
 }
 
 void
-nsScriptLoader::ContinueParserAsync(nsScriptLoadRequest* aParserBlockingRequest)
+ScriptLoader::ContinueParserAsync(ScriptLoadRequest* aParserBlockingRequest)
 {
   aParserBlockingRequest->mElement->ContinueParserAsync();
 }
 
 uint32_t
-nsScriptLoader::NumberOfProcessors()
+ScriptLoader::NumberOfProcessors()
 {
   if (mNumberOfProcessors > 0)
     return mNumberOfProcessors;
@@ -2621,7 +2341,7 @@ nsScriptLoader::NumberOfProcessors()
 }
 
 void
-nsScriptLoader::MaybeMoveToLoadedList(nsScriptLoadRequest* aRequest)
+ScriptLoader::MaybeMoveToLoadedList(ScriptLoadRequest* aRequest)
 {
   MOZ_ASSERT(aRequest->IsReadyToRun());
 
@@ -2631,17 +2351,17 @@ nsScriptLoader::MaybeMoveToLoadedList(nsScriptLoadRequest* aRequest)
   if (aRequest->mIsAsync) {
     MOZ_ASSERT(aRequest->isInList());
     if (aRequest->isInList()) {
-      RefPtr<nsScriptLoadRequest> req = mLoadingAsyncRequests.Steal(aRequest);
+      RefPtr<ScriptLoadRequest> req = mLoadingAsyncRequests.Steal(aRequest);
       mLoadedAsyncRequests.AppendElement(req);
     }
   }
 }
 
 nsresult
-nsScriptLoader::PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
-                                     nsIIncrementalStreamLoader* aLoader,
-                                     nsresult aStatus,
-                                     mozilla::Vector<char16_t> &aString)
+ScriptLoader::PrepareLoadedRequest(ScriptLoadRequest* aRequest,
+                                   nsIIncrementalStreamLoader* aLoader,
+                                   nsresult aStatus,
+                                   mozilla::Vector<char16_t> &aString)
 {
   if (NS_FAILED(aStatus)) {
     return aStatus;
@@ -2713,7 +2433,7 @@ nsScriptLoader::PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
                "aRequest should be pending!");
 
   if (aRequest->IsModuleRequest()) {
-    nsModuleLoadRequest* request = aRequest->AsModuleRequest();
+    ModuleLoadRequest* request = aRequest->AsModuleRequest();
 
     // When loading a module, only responses with a JavaScript MIME type are
     // acceptable.
@@ -2744,7 +2464,7 @@ nsScriptLoader::PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
     MOZ_ASSERT(!aRequest->IsModuleRequest());
     nsresult rv = AttemptAsyncScriptCompile(aRequest);
     if (rv == NS_OK) {
-      MOZ_ASSERT(aRequest->mProgress == nsScriptLoadRequest::Progress::Compiling,
+      MOZ_ASSERT(aRequest->mProgress == ScriptLoadRequest::Progress::Compiling,
                  "Request should be off-thread compiling now.");
       return NS_OK;
     }
@@ -2763,7 +2483,7 @@ nsScriptLoader::PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
 }
 
 void
-nsScriptLoader::ParsingComplete(bool aTerminated)
+ScriptLoader::ParsingComplete(bool aTerminated)
 {
   if (mDeferEnabled) {
     // Have to check because we apparently get ParsingComplete
@@ -2789,12 +2509,12 @@ nsScriptLoader::ParsingComplete(bool aTerminated)
 }
 
 void
-nsScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
-                           const nsAString &aType,
-                           const nsAString &aCrossOrigin,
-                           const nsAString& aIntegrity,
-                           bool aScriptFromHead,
-                           const mozilla::net::ReferrerPolicy aReferrerPolicy)
+ScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
+                         const nsAString &aType,
+                         const nsAString &aCrossOrigin,
+                         const nsAString& aIntegrity,
+                         bool aScriptFromHead,
+                         const mozilla::net::ReferrerPolicy aReferrerPolicy)
 {
   NS_ENSURE_TRUE_VOID(mDocument);
   // Check to see if scripts has been turned off.
@@ -2810,7 +2530,7 @@ nsScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
   SRIMetadata sriMetadata;
   if (!aIntegrity.IsEmpty()) {
     MOZ_LOG(SRILogHelper::GetSriLog(), mozilla::LogLevel::Debug,
-           ("nsScriptLoader::PreloadURI, integrity=%s",
+           ("ScriptLoader::PreloadURI, integrity=%s",
             NS_ConvertUTF16toUTF8(aIntegrity).get()));
     nsAutoCString sourceUri;
     if (mDocument->GetDocumentURI()) {
@@ -2819,8 +2539,8 @@ nsScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
     SRICheck::IntegrityMetadata(aIntegrity, sourceUri, mReporter, &sriMetadata);
   }
 
-  RefPtr<nsScriptLoadRequest> request =
-    CreateLoadRequest(nsScriptKind::Classic, nullptr, 0,
+  RefPtr<ScriptLoadRequest> request =
+    CreateLoadRequest(ScriptKind::Classic, nullptr, 0,
                       Element::StringToCORSMode(aCrossOrigin), sriMetadata);
   request->mURI = aURI;
   request->mIsInline = false;
@@ -2837,7 +2557,7 @@ nsScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
 }
 
 void
-nsScriptLoader::AddDeferRequest(nsScriptLoadRequest* aRequest)
+ScriptLoader::AddDeferRequest(ScriptLoadRequest* aRequest)
 {
   aRequest->mIsDefer = true;
   mDeferRequests.AppendElement(aRequest);
@@ -2850,7 +2570,7 @@ nsScriptLoader::AddDeferRequest(nsScriptLoadRequest* aRequest)
 }
 
 bool
-nsScriptLoader::MaybeRemovedDeferRequests()
+ScriptLoader::MaybeRemovedDeferRequests()
 {
   if (mDeferRequests.isEmpty() && mDocument &&
       mBlockingDOMContentLoaded) {
@@ -2861,201 +2581,5 @@ nsScriptLoader::MaybeRemovedDeferRequests()
   return false;
 }
 
-//////////////////////////////////////////////////////////////
-// nsScriptLoadHandler
-//////////////////////////////////////////////////////////////
-
-nsScriptLoadHandler::nsScriptLoadHandler(nsScriptLoader *aScriptLoader,
-                                         nsScriptLoadRequest *aRequest,
-                                         mozilla::dom::SRICheckDataVerifier *aSRIDataVerifier)
-  : mScriptLoader(aScriptLoader),
-    mRequest(aRequest),
-    mSRIDataVerifier(aSRIDataVerifier),
-    mSRIStatus(NS_OK),
-    mDecoder(),
-    mBuffer()
-{}
-
-nsScriptLoadHandler::~nsScriptLoadHandler()
-{}
-
-NS_IMPL_ISUPPORTS(nsScriptLoadHandler, nsIIncrementalStreamLoaderObserver)
-
-NS_IMETHODIMP
-nsScriptLoadHandler::OnIncrementalData(nsIIncrementalStreamLoader* aLoader,
-                                       nsISupports* aContext,
-                                       uint32_t aDataLength,
-                                       const uint8_t* aData,
-                                       uint32_t *aConsumedLength)
-{
-  if (mRequest->IsCanceled()) {
-    // If request cancelled, ignore any incoming data.
-    *aConsumedLength = aDataLength;
-    return NS_OK;
-  }
-
-  if (!EnsureDecoder(aLoader, aData, aDataLength,
-                     /* aEndOfStream = */ false)) {
-    return NS_OK;
-  }
-
-  // Below we will/shall consume entire data chunk.
-  *aConsumedLength = aDataLength;
-
-  // Decoder has already been initialized. -- trying to decode all loaded bytes.
-  nsresult rv = TryDecodeRawData(aData, aDataLength,
-                                 /* aEndOfStream = */ false);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  // If SRI is required for this load, appending new bytes to the hash.
-  if (mSRIDataVerifier && NS_SUCCEEDED(mSRIStatus)) {
-    mSRIStatus = mSRIDataVerifier->Update(aDataLength, aData);
-  }
-
-  return rv;
-}
-
-nsresult
-nsScriptLoadHandler::TryDecodeRawData(const uint8_t* aData,
-                                      uint32_t aDataLength,
-                                      bool aEndOfStream)
-{
-  int32_t srcLen = aDataLength;
-  const char* src = reinterpret_cast<const char *>(aData);
-  int32_t dstLen;
-  nsresult rv =
-    mDecoder->GetMaxLength(src, srcLen, &dstLen);
-
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  uint32_t haveRead = mBuffer.length();
-
-  CheckedInt<uint32_t> capacity = haveRead;
-  capacity += dstLen;
-
-  if (!capacity.isValid() || !mBuffer.reserve(capacity.value())) {
-    return NS_ERROR_OUT_OF_MEMORY;
-  }
-
-  rv = mDecoder->Convert(src,
-                      &srcLen,
-                      mBuffer.begin() + haveRead,
-                      &dstLen);
-
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  haveRead += dstLen;
-  MOZ_ASSERT(haveRead <= capacity.value(), "mDecoder produced more data than expected");
-  MOZ_ALWAYS_TRUE(mBuffer.resizeUninitialized(haveRead));
-
-  return NS_OK;
-}
-
-bool
-nsScriptLoadHandler::EnsureDecoder(nsIIncrementalStreamLoader *aLoader,
-                                   const uint8_t* aData,
-                                   uint32_t aDataLength,
-                                   bool aEndOfStream)
-{
-  // Check if decoder has already been created.
-  if (mDecoder) {
-    return true;
-  }
-
-  nsAutoCString charset;
-
-  // JavaScript modules are always UTF-8.
-  if (mRequest->IsModuleRequest()) {
-    charset = "UTF-8";
-    mDecoder = EncodingUtils::DecoderForEncoding(charset);
-    return true;
-  }
-
-  // Determine if BOM check should be done.  This occurs either
-  // if end-of-stream has been reached, or at least 3 bytes have
-  // been read from input.
-  if (!aEndOfStream && (aDataLength < 3)) {
-    return false;
-  }
-
-  // Do BOM detection.
-  if (nsContentUtils::CheckForBOM(aData, aDataLength, charset)) {
-    mDecoder = EncodingUtils::DecoderForEncoding(charset);
-    return true;
-  }
-
-  // BOM detection failed, check content stream for charset.
-  nsCOMPtr<nsIRequest> req;
-  nsresult rv = aLoader->GetRequest(getter_AddRefs(req));
-  NS_ASSERTION(req, "StreamLoader's request went away prematurely");
-  NS_ENSURE_SUCCESS(rv, false);
-
-  nsCOMPtr<nsIChannel> channel = do_QueryInterface(req);
-
-  if (channel &&
-      NS_SUCCEEDED(channel->GetContentCharset(charset)) &&
-      EncodingUtils::FindEncodingForLabel(charset, charset)) {
-    mDecoder = EncodingUtils::DecoderForEncoding(charset);
-    return true;
-  }
-
-  // Check the hint charset from the script element or preload
-  // request.
-  nsAutoString hintCharset;
-  if (!mRequest->IsPreload()) {
-    mRequest->mElement->GetScriptCharset(hintCharset);
-  } else {
-    nsTArray<nsScriptLoader::PreloadInfo>::index_type i =
-      mScriptLoader->mPreloads.IndexOf(mRequest, 0,
-            nsScriptLoader::PreloadRequestComparator());
-
-    NS_ASSERTION(i != mScriptLoader->mPreloads.NoIndex,
-                 "Incorrect preload bookkeeping");
-    hintCharset = mScriptLoader->mPreloads[i].mCharset;
-  }
-
-  if (EncodingUtils::FindEncodingForLabel(hintCharset, charset)) {
-    mDecoder = EncodingUtils::DecoderForEncoding(charset);
-    return true;
-  }
-
-  // Get the charset from the charset of the document.
-  if (mScriptLoader->mDocument) {
-    charset = mScriptLoader->mDocument->GetDocumentCharacterSet();
-    mDecoder = EncodingUtils::DecoderForEncoding(charset);
-    return true;
-  }
-
-  // Curiously, there are various callers that don't pass aDocument. The
-  // fallback in the old code was ISO-8859-1, which behaved like
-  // windows-1252. Saying windows-1252 for clarity and for compliance
-  // with the Encoding Standard.
-  charset = "windows-1252";
-  mDecoder = EncodingUtils::DecoderForEncoding(charset);
-  return true;
-}
-
-NS_IMETHODIMP
-nsScriptLoadHandler::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
-                                      nsISupports* aContext,
-                                      nsresult aStatus,
-                                      uint32_t aDataLength,
-                                      const uint8_t* aData)
-{
-  if (!mRequest->IsCanceled()) {
-    DebugOnly<bool> encoderSet =
-      EnsureDecoder(aLoader, aData, aDataLength, /* aEndOfStream = */ true);
-    MOZ_ASSERT(encoderSet);
-    DebugOnly<nsresult> rv = TryDecodeRawData(aData, aDataLength,
-                                              /* aEndOfStream = */ true);
-
-    // If SRI is required for this load, appending new bytes to the hash.
-    if (mSRIDataVerifier && NS_SUCCEEDED(mSRIStatus)) {
-      mSRIStatus = mSRIDataVerifier->Update(aDataLength, aData);
-    }
-  }
-
-  // we have to mediate and use mRequest.
-  return mScriptLoader->OnStreamComplete(aLoader, mRequest, aStatus, mSRIStatus,
-                                         mBuffer, mSRIDataVerifier);
-}
+} // dom namespace
+} // mozilla namespace
diff --git a/dom/base/nsScriptLoader.h b/dom/script/ScriptLoader.h
similarity index 72%
rename from dom/base/nsScriptLoader.h
rename to dom/script/ScriptLoader.h
index a00239be5..3c428deea 100644
--- a/dom/base/nsScriptLoader.h
+++ b/dom/script/ScriptLoader.h
@@ -4,12 +4,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/*
- * A class that handles loading and evaluation of <script> elements.
- */
-
-#ifndef __nsScriptLoader_h__
-#define __nsScriptLoader_h__
+#ifndef mozilla_dom_ScriptLoader_h
+#define mozilla_dom_ScriptLoader_h
 
 #include "nsCOMPtr.h"
 #include "nsRefPtrHashtable.h"
@@ -25,14 +21,10 @@
 #include "mozilla/CORSMode.h"
 #include "mozilla/dom/SRIMetadata.h"
 #include "mozilla/dom/SRICheck.h"
-#include "mozilla/LinkedList.h"
 #include "mozilla/MozPromise.h"
 #include "mozilla/net/ReferrerPolicy.h"
 #include "mozilla/Vector.h"
 
-class nsModuleLoadRequest;
-class nsModuleScript;
-class nsScriptLoadRequestList;
 class nsIURI;
 
 namespace JS {
@@ -41,37 +33,39 @@ namespace JS {
 
 namespace mozilla {
 namespace dom {
+
 class AutoJSAPI;
-} // namespace dom
-} // namespace mozilla
+class ModuleLoadRequest;
+class ModuleScript;
+class ScriptLoadRequestList;
 
 //////////////////////////////////////////////////////////////
 // Per-request data structure
 //////////////////////////////////////////////////////////////
 
-enum class nsScriptKind {
+enum class ScriptKind {
   Classic,
   Module
 };
 
-class nsScriptLoadRequest : public nsISupports,
-                            private mozilla::LinkedListElement<nsScriptLoadRequest>
+class ScriptLoadRequest : public nsISupports,
+                          private mozilla::LinkedListElement<ScriptLoadRequest>
 {
-  typedef LinkedListElement<nsScriptLoadRequest> super;
+  typedef LinkedListElement<ScriptLoadRequest> super;
 
-  // Allow LinkedListElement<nsScriptLoadRequest> to cast us to itself as needed.
-  friend class mozilla::LinkedListElement<nsScriptLoadRequest>;
-  friend class nsScriptLoadRequestList;
+  // Allow LinkedListElement<ScriptLoadRequest> to cast us to itself as needed.
+  friend class mozilla::LinkedListElement<ScriptLoadRequest>;
+  friend class ScriptLoadRequestList;
 
 protected:
-  virtual ~nsScriptLoadRequest();
+  virtual ~ScriptLoadRequest();
 
 public:
-  nsScriptLoadRequest(nsScriptKind aKind,
-                      nsIScriptElement* aElement,
-                      uint32_t aVersion,
-                      mozilla::CORSMode aCORSMode,
-                      const mozilla::dom::SRIMetadata &aIntegrity)
+  ScriptLoadRequest(ScriptKind aKind,
+                    nsIScriptElement* aElement,
+                    uint32_t aVersion,
+                    mozilla::CORSMode aCORSMode,
+                    const mozilla::dom::SRIMetadata &aIntegrity)
     : mKind(aKind),
       mElement(aElement),
       mProgress(Progress::Loading),
@@ -95,14 +89,14 @@ public:
   }
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
-  NS_DECL_CYCLE_COLLECTION_CLASS(nsScriptLoadRequest)
+  NS_DECL_CYCLE_COLLECTION_CLASS(ScriptLoadRequest)
 
   bool IsModuleRequest() const
   {
-    return mKind == nsScriptKind::Module;
+    return mKind == ScriptKind::Module;
   }
 
-  nsModuleLoadRequest* AsModuleRequest();
+  ModuleLoadRequest* AsModuleRequest();
 
   void FireScriptAvailable(nsresult aResult)
   {
@@ -154,7 +148,7 @@ public:
   using super::getNext;
   using super::isInList;
 
-  const nsScriptKind mKind;
+  const ScriptKind mKind;
   nsCOMPtr<nsIScriptElement> mElement;
   Progress mProgress;     // Are we still waiting for a load to complete?
   bool mIsInline;         // Is the script inline or loaded?
@@ -179,23 +173,23 @@ public:
   mozilla::net::ReferrerPolicy mReferrerPolicy;
 };
 
-class nsScriptLoadRequestList : private mozilla::LinkedList<nsScriptLoadRequest>
+class ScriptLoadRequestList : private mozilla::LinkedList<ScriptLoadRequest>
 {
-  typedef mozilla::LinkedList<nsScriptLoadRequest> super;
+  typedef mozilla::LinkedList<ScriptLoadRequest> super;
 
 public:
-  ~nsScriptLoadRequestList();
+  ~ScriptLoadRequestList();
 
   void Clear();
 
 #ifdef DEBUG
-  bool Contains(nsScriptLoadRequest* aElem) const;
+  bool Contains(ScriptLoadRequest* aElem) const;
 #endif // DEBUG
 
   using super::getFirst;
   using super::isEmpty;
 
-  void AppendElement(nsScriptLoadRequest* aElem)
+  void AppendElement(ScriptLoadRequest* aElem)
   {
     MOZ_ASSERT(!aElem->isInList());
     NS_ADDREF(aElem);
@@ -203,36 +197,37 @@ public:
   }
 
   MOZ_MUST_USE
-  already_AddRefed<nsScriptLoadRequest> Steal(nsScriptLoadRequest* aElem)
+  already_AddRefed<ScriptLoadRequest> Steal(ScriptLoadRequest* aElem)
   {
     aElem->removeFrom(*this);
     return dont_AddRef(aElem);
   }
 
   MOZ_MUST_USE
-  already_AddRefed<nsScriptLoadRequest> StealFirst()
+  already_AddRefed<ScriptLoadRequest> StealFirst()
   {
     MOZ_ASSERT(!isEmpty());
     return Steal(getFirst());
   }
 
-  void Remove(nsScriptLoadRequest* aElem)
+  void Remove(ScriptLoadRequest* aElem)
   {
     aElem->removeFrom(*this);
     NS_RELEASE(aElem);
   }
 };
+class ScriptLoadHandler;
 
 //////////////////////////////////////////////////////////////
 // Script loader implementation
 //////////////////////////////////////////////////////////////
 
-class nsScriptLoader final : public nsISupports
+class ScriptLoader final : public nsISupports
 {
   class MOZ_STACK_CLASS AutoCurrentScriptUpdater
   {
   public:
-    AutoCurrentScriptUpdater(nsScriptLoader* aScriptLoader,
+    AutoCurrentScriptUpdater(ScriptLoader* aScriptLoader,
                              nsIScriptElement* aCurrentScript)
       : mOldScript(aScriptLoader->mCurrentScript)
       , mScriptLoader(aScriptLoader)
@@ -245,19 +240,19 @@ class nsScriptLoader final : public nsISupports
     }
   private:
     nsCOMPtr<nsIScriptElement> mOldScript;
-    nsScriptLoader* mScriptLoader;
+    ScriptLoader* mScriptLoader;
   };
 
-  friend class nsModuleLoadRequest;
-  friend class nsScriptRequestProcessor;
-  friend class nsScriptLoadHandler;
+  friend class ModuleLoadRequest;
+  friend class ScriptRequestProcessor;
+  friend class ScriptLoadHandler;
   friend class AutoCurrentScriptUpdater;
 
 public:
-  explicit nsScriptLoader(nsIDocument* aDocument);
+  explicit ScriptLoader(nsIDocument* aDocument);
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
-  NS_DECL_CYCLE_COLLECTION_CLASS(nsScriptLoader)
+  NS_DECL_CYCLE_COLLECTION_CLASS(ScriptLoader)
 
   /**
    * The loader maintains a weak reference to the document with
@@ -395,7 +390,7 @@ public:
 
   /**
    * Handle the completion of a stream.  This is called by the
-   * nsScriptLoadHandler object which observes the IncrementalStreamLoader
+   * ScriptLoadHandler object which observes the IncrementalStreamLoader
    * loading the script.
    */
   nsresult OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
@@ -463,17 +458,17 @@ public:
    * Process a request that was deferred so that the script could be compiled
    * off thread.
    */
-  nsresult ProcessOffThreadRequest(nsScriptLoadRequest *aRequest);
+  nsresult ProcessOffThreadRequest(ScriptLoadRequest *aRequest);
 
-  bool AddPendingChildLoader(nsScriptLoader* aChild) {
+  bool AddPendingChildLoader(ScriptLoader* aChild) {
     return mPendingChildLoaders.AppendElement(aChild) != nullptr;
   }
 
 private:
-  virtual ~nsScriptLoader();
+  virtual ~ScriptLoader();
 
-  nsScriptLoadRequest* CreateLoadRequest(
-    nsScriptKind aKind,
+  ScriptLoadRequest* CreateLoadRequest(
+    ScriptKind aKind,
     nsIScriptElement* aElement,
     uint32_t aVersion,
     mozilla::CORSMode aCORSMode,
@@ -482,12 +477,12 @@ private:
   /**
    * Unblocks the creator parser of the parser-blocking scripts.
    */
-  void UnblockParser(nsScriptLoadRequest* aParserBlockingRequest);
+  void UnblockParser(ScriptLoadRequest* aParserBlockingRequest);
 
   /**
    * Asynchronously resumes the creator parser of the parser-blocking scripts.
    */
-  void ContinueParserAsync(nsScriptLoadRequest* aParserBlockingRequest);
+  void ContinueParserAsync(ScriptLoadRequest* aParserBlockingRequest);
 
 
   /**
@@ -502,7 +497,7 @@ private:
   /**
    * Start a load for aRequest's URI.
    */
-  nsresult StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
+  nsresult StartLoad(ScriptLoadRequest *aRequest, const nsAString &aType,
                      bool aScriptFromHead);
 
   /**
@@ -539,83 +534,83 @@ private:
     return mEnabled && !mBlockerCount;
   }
 
-  nsresult AttemptAsyncScriptCompile(nsScriptLoadRequest* aRequest);
-  nsresult ProcessRequest(nsScriptLoadRequest* aRequest);
-  nsresult CompileOffThreadOrProcessRequest(nsScriptLoadRequest* aRequest);
+  nsresult AttemptAsyncScriptCompile(ScriptLoadRequest* aRequest);
+  nsresult ProcessRequest(ScriptLoadRequest* aRequest);
+  nsresult CompileOffThreadOrProcessRequest(ScriptLoadRequest* aRequest);
   void FireScriptAvailable(nsresult aResult,
-                           nsScriptLoadRequest* aRequest);
+                           ScriptLoadRequest* aRequest);
   void FireScriptEvaluated(nsresult aResult,
-                           nsScriptLoadRequest* aRequest);
-  nsresult EvaluateScript(nsScriptLoadRequest* aRequest);
+                           ScriptLoadRequest* aRequest);
+  nsresult EvaluateScript(ScriptLoadRequest* aRequest);
 
   already_AddRefed<nsIScriptGlobalObject> GetScriptGlobalObject();
   nsresult FillCompileOptionsForRequest(const mozilla::dom::AutoJSAPI& jsapi,
-                                        nsScriptLoadRequest* aRequest,
+                                        ScriptLoadRequest* aRequest,
                                         JS::Handle<JSObject*> aScopeChain,
                                         JS::CompileOptions* aOptions);
 
   uint32_t NumberOfProcessors();
-  nsresult PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
+  nsresult PrepareLoadedRequest(ScriptLoadRequest* aRequest,
                                 nsIIncrementalStreamLoader* aLoader,
                                 nsresult aStatus,
                                 mozilla::Vector<char16_t> &aString);
 
-  void AddDeferRequest(nsScriptLoadRequest* aRequest);
+  void AddDeferRequest(ScriptLoadRequest* aRequest);
   bool MaybeRemovedDeferRequests();
 
-  void MaybeMoveToLoadedList(nsScriptLoadRequest* aRequest);
+  void MaybeMoveToLoadedList(ScriptLoadRequest* aRequest);
 
-  JS::SourceBufferHolder GetScriptSource(nsScriptLoadRequest* aRequest,
+  JS::SourceBufferHolder GetScriptSource(ScriptLoadRequest* aRequest,
                                          nsAutoString& inlineData);
 
   bool ModuleScriptsEnabled();
 
-  void SetModuleFetchStarted(nsModuleLoadRequest *aRequest);
-  void SetModuleFetchFinishedAndResumeWaitingRequests(nsModuleLoadRequest *aRequest,
+  void SetModuleFetchStarted(ModuleLoadRequest *aRequest);
+  void SetModuleFetchFinishedAndResumeWaitingRequests(ModuleLoadRequest *aRequest,
                                                       nsresult aResult);
 
-  bool IsFetchingModule(nsModuleLoadRequest *aRequest) const;
+  bool IsFetchingModule(ModuleLoadRequest *aRequest) const;
 
-  bool ModuleMapContainsModule(nsModuleLoadRequest *aRequest) const;
-  RefPtr<mozilla::GenericPromise> WaitForModuleFetch(nsModuleLoadRequest *aRequest);
-  nsModuleScript* GetFetchedModule(nsIURI* aURL) const;
+  bool ModuleMapContainsModule(ModuleLoadRequest *aRequest) const;
+  RefPtr<mozilla::GenericPromise> WaitForModuleFetch(ModuleLoadRequest *aRequest);
+  ModuleScript* GetFetchedModule(nsIURI* aURL) const;
 
   friend bool
   HostResolveImportedModule(JSContext* aCx, unsigned argc, JS::Value* vp);
 
-  nsresult CreateModuleScript(nsModuleLoadRequest* aRequest);
-  nsresult ProcessFetchedModuleSource(nsModuleLoadRequest* aRequest);
-  void ProcessLoadedModuleTree(nsModuleLoadRequest* aRequest);
-  bool InstantiateModuleTree(nsModuleLoadRequest* aRequest);
-  void StartFetchingModuleDependencies(nsModuleLoadRequest* aRequest);
+  nsresult CreateModuleScript(ModuleLoadRequest* aRequest);
+  nsresult ProcessFetchedModuleSource(ModuleLoadRequest* aRequest);
+  void ProcessLoadedModuleTree(ModuleLoadRequest* aRequest);
+  bool InstantiateModuleTree(ModuleLoadRequest* aRequest);
+  void StartFetchingModuleDependencies(ModuleLoadRequest* aRequest);
 
   RefPtr<mozilla::GenericPromise>
-  StartFetchingModuleAndDependencies(nsModuleLoadRequest* aRequest, nsIURI* aURI);
+  StartFetchingModuleAndDependencies(ModuleLoadRequest* aRequest, nsIURI* aURI);
 
   nsIDocument* mDocument;                   // [WEAK]
   nsCOMArray<nsIScriptLoaderObserver> mObservers;
-  nsScriptLoadRequestList mNonAsyncExternalScriptInsertedRequests;
+  ScriptLoadRequestList mNonAsyncExternalScriptInsertedRequests;
   // mLoadingAsyncRequests holds async requests while they're loading; when they
   // have been loaded they are moved to mLoadedAsyncRequests.
-  nsScriptLoadRequestList mLoadingAsyncRequests;
-  nsScriptLoadRequestList mLoadedAsyncRequests;
-  nsScriptLoadRequestList mDeferRequests;
-  nsScriptLoadRequestList mXSLTRequests;
-  RefPtr<nsScriptLoadRequest> mParserBlockingRequest;
+  ScriptLoadRequestList mLoadingAsyncRequests;
+  ScriptLoadRequestList mLoadedAsyncRequests;
+  ScriptLoadRequestList mDeferRequests;
+  ScriptLoadRequestList mXSLTRequests;
+  RefPtr<ScriptLoadRequest> mParserBlockingRequest;
 
   // In mRequests, the additional information here is stored by the element.
   struct PreloadInfo {
-    RefPtr<nsScriptLoadRequest> mRequest;
+    RefPtr<ScriptLoadRequest> mRequest;
     nsString mCharset;
   };
 
-  friend void ImplCycleCollectionUnlink(nsScriptLoader::PreloadInfo& aField);
+  friend void ImplCycleCollectionUnlink(ScriptLoader::PreloadInfo& aField);
   friend void ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
-                                          nsScriptLoader::PreloadInfo& aField,
+                                          ScriptLoader::PreloadInfo& aField,
                                           const char* aName, uint32_t aFlags);
 
   struct PreloadRequestComparator {
-    bool Equals(const PreloadInfo &aPi, nsScriptLoadRequest * const &aRequest)
+    bool Equals(const PreloadInfo &aPi, ScriptLoadRequest * const &aRequest)
         const
     {
       return aRequest == aPi.mRequest;
@@ -628,7 +623,7 @@ private:
 
   nsCOMPtr<nsIScriptElement> mCurrentScript;
   nsCOMPtr<nsIScriptElement> mCurrentParserInsertedScript;
-  nsTArray< RefPtr<nsScriptLoader> > mPendingChildLoaders;
+  nsTArray< RefPtr<ScriptLoader> > mPendingChildLoaders;
   uint32_t mParserBlockingBlockerCount;
   uint32_t mBlockerCount;
   uint32_t mNumberOfProcessors;
@@ -639,58 +634,11 @@ private:
 
   // Module map
   nsRefPtrHashtable<nsURIHashKey, mozilla::GenericPromise::Private> mFetchingModules;
-  nsRefPtrHashtable<nsURIHashKey, nsModuleScript> mFetchedModules;
+  nsRefPtrHashtable<nsURIHashKey, ModuleScript> mFetchedModules;
 
   nsCOMPtr<nsIConsoleReportCollector> mReporter;
 };
 
-class nsScriptLoadHandler final : public nsIIncrementalStreamLoaderObserver
-{
-public:
-  explicit nsScriptLoadHandler(nsScriptLoader* aScriptLoader,
-                               nsScriptLoadRequest *aRequest,
-                               mozilla::dom::SRICheckDataVerifier *aSRIDataVerifier);
-
-  NS_DECL_ISUPPORTS
-  NS_DECL_NSIINCREMENTALSTREAMLOADEROBSERVER
-
-private:
-  virtual ~nsScriptLoadHandler();
-
-  /*
-   * Try to decode some raw data.
-   */
-  nsresult TryDecodeRawData(const uint8_t* aData, uint32_t aDataLength,
-                            bool aEndOfStream);
-
-  /*
-   * Discover the charset by looking at the stream data, the script
-   * tag, and other indicators.  Returns true if charset has been
-   * discovered.
-   */
-  bool EnsureDecoder(nsIIncrementalStreamLoader *aLoader,
-                     const uint8_t* aData, uint32_t aDataLength,
-                     bool aEndOfStream);
-
-  // ScriptLoader which will handle the parsed script.
-  RefPtr<nsScriptLoader>        mScriptLoader;
-
-  // The nsScriptLoadRequest for this load.
-  RefPtr<nsScriptLoadRequest>   mRequest;
-
-  // SRI data verifier.
-  nsAutoPtr<mozilla::dom::SRICheckDataVerifier> mSRIDataVerifier;
-
-  // Status of SRI data operations.
-  nsresult                      mSRIStatus;
-
-  // Unicode decoder for charset.
-  nsCOMPtr<nsIUnicodeDecoder>   mDecoder;
-
-  // Accumulated decoded char buffer.
-  mozilla::Vector<char16_t>     mBuffer;
-};
-
 class nsAutoScriptLoaderDisabler
 {
 public:
@@ -711,7 +659,10 @@ public:
   }
 
   bool mWasEnabled;
-  RefPtr<nsScriptLoader> mLoader;
+  RefPtr<ScriptLoader> mLoader;
 };
 
-#endif //__nsScriptLoader_h__
+} // namespace dom
+} // namespace mozilla
+
+#endif //mozilla_dom_ScriptLoader_h
diff --git a/dom/base/ScriptSettings.cpp b/dom/script/ScriptSettings.cpp
similarity index 100%
rename from dom/base/ScriptSettings.cpp
rename to dom/script/ScriptSettings.cpp
diff --git a/dom/base/ScriptSettings.h b/dom/script/ScriptSettings.h
similarity index 100%
rename from dom/base/ScriptSettings.h
rename to dom/script/ScriptSettings.h
diff --git a/dom/script/moz.build b/dom/script/moz.build
new file mode 100644
index 000000000..280850ed4
--- /dev/null
+++ b/dom/script/moz.build
@@ -0,0 +1,36 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+XPIDL_SOURCES += [
+    'nsIScriptLoaderObserver.idl',
+]
+
+XPIDL_MODULE = 'dom'
+
+EXPORTS += ['nsIScriptElement.h']
+
+EXPORTS.mozilla.dom += [
+    'ScriptElement.h',
+    'ScriptLoader.h',
+    'ScriptSettings.h',
+]
+
+SOURCES += [
+    'ModuleLoadRequest.cpp',
+    'ModuleScript.cpp',
+    'ScriptElement.cpp',
+    'ScriptLoader.cpp',
+    'ScriptLoadHandler.cpp',
+    'ScriptSettings.cpp',
+]
+
+LOCAL_INCLUDES += [
+    '/dom/base',
+    '/dom/workers',
+]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+FINAL_LIBRARY = 'xul'
diff --git a/dom/base/nsIScriptElement.h b/dom/script/nsIScriptElement.h
similarity index 100%
rename from dom/base/nsIScriptElement.h
rename to dom/script/nsIScriptElement.h
diff --git a/dom/base/nsIScriptLoaderObserver.idl b/dom/script/nsIScriptLoaderObserver.idl
similarity index 100%
rename from dom/base/nsIScriptLoaderObserver.idl
rename to dom/script/nsIScriptLoaderObserver.idl
diff --git a/dom/svg/SVGScriptElement.cpp b/dom/svg/SVGScriptElement.cpp
index 0cc827b9f..7adce2f46 100644
--- a/dom/svg/SVGScriptElement.cpp
+++ b/dom/svg/SVGScriptElement.cpp
@@ -42,7 +42,7 @@ NS_IMPL_ISUPPORTS_INHERITED(SVGScriptElement, SVGScriptElementBase,
 SVGScriptElement::SVGScriptElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo,
                                    FromParser aFromParser)
   : SVGScriptElementBase(aNodeInfo)
-  , nsScriptElement(aFromParser)
+  , ScriptElement(aFromParser)
 {
   AddMutationObserver(this);
 }
@@ -168,7 +168,7 @@ SVGScriptElement::FreezeUriAsyncDefer()
 }
 
 //----------------------------------------------------------------------
-// nsScriptElement methods
+// ScriptElement methods
 
 bool
 SVGScriptElement::HasScriptContent()
diff --git a/dom/svg/SVGScriptElement.h b/dom/svg/SVGScriptElement.h
index d3a233b72..79a3de70d 100644
--- a/dom/svg/SVGScriptElement.h
+++ b/dom/svg/SVGScriptElement.h
@@ -10,7 +10,7 @@
 #include "nsSVGElement.h"
 #include "nsCOMPtr.h"
 #include "nsSVGString.h"
-#include "nsScriptElement.h"
+#include "mozilla/dom/ScriptElement.h"
 
 class nsIDocument;
 
@@ -24,7 +24,7 @@ namespace dom {
 typedef nsSVGElement SVGScriptElementBase;
 
 class SVGScriptElement final : public SVGScriptElementBase,
-                               public nsScriptElement
+                               public ScriptElement
 {
 protected:
   friend nsresult (::NS_NewSVGScriptElement(nsIContent **aResult,
@@ -47,7 +47,7 @@ public:
   virtual void FreezeUriAsyncDefer() override;
   virtual CORSMode GetCORSMode() const override;
 
-  // nsScriptElement
+  // ScriptElement
   virtual bool HasScriptContent() override;
 
   // nsIContent specializations:
diff --git a/dom/workers/ScriptLoader.cpp b/dom/workers/ScriptLoader.cpp
index 56b18441e..bcec94dcb 100644
--- a/dom/workers/ScriptLoader.cpp
+++ b/dom/workers/ScriptLoader.cpp
@@ -34,7 +34,6 @@
 #include "nsIPipe.h"
 #include "nsIOutputStream.h"
 #include "nsPrintfCString.h"
-#include "nsScriptLoader.h"
 #include "nsString.h"
 #include "nsStreamUtils.h"
 #include "nsTArray.h"
@@ -58,6 +57,7 @@
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/PromiseNativeHandler.h"
 #include "mozilla/dom/Response.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/SRILogHelper.h"
 #include "mozilla/UniquePtr.h"
@@ -1075,14 +1075,14 @@ private:
     // May be null.
     nsIDocument* parentDoc = mWorkerPrivate->GetDocument();
 
-    // Use the regular nsScriptLoader for this grunt work! Should be just fine
+    // Use the regular ScriptLoader for this grunt work! Should be just fine
     // because we're running on the main thread.
     // Unlike <script> tags, Worker scripts are always decoded as UTF-8,
     // per spec. So we explicitly pass in the charset hint.
-    rv = nsScriptLoader::ConvertToUTF16(aLoadInfo.mChannel, aString, aStringLen,
-                                        NS_LITERAL_STRING("UTF-8"), parentDoc,
-                                        aLoadInfo.mScriptTextBuf,
-                                        aLoadInfo.mScriptTextLength);
+    rv = ScriptLoader::ConvertToUTF16(aLoadInfo.mChannel, aString, aStringLen,
+                                      NS_LITERAL_STRING("UTF-8"), parentDoc,
+                                      aLoadInfo.mScriptTextBuf,
+                                      aLoadInfo.mScriptTextLength);
     if (NS_FAILED(rv)) {
       return rv;
     }
@@ -1289,10 +1289,10 @@ private:
     MOZ_ASSERT(!loadInfo.mScriptTextBuf);
 
     nsresult rv =
-      nsScriptLoader::ConvertToUTF16(nullptr, aString, aStringLen,
-                                     NS_LITERAL_STRING("UTF-8"), parentDoc,
-                                     loadInfo.mScriptTextBuf,
-                                     loadInfo.mScriptTextLength);
+      ScriptLoader::ConvertToUTF16(nullptr, aString, aStringLen,
+                                   NS_LITERAL_STRING("UTF-8"), parentDoc,
+                                   loadInfo.mScriptTextBuf,
+                                   loadInfo.mScriptTextLength);
     if (NS_SUCCEEDED(rv) && IsMainWorkerScript()) {
       nsCOMPtr<nsIURI> finalURI;
       rv = NS_NewURI(getter_AddRefs(finalURI), loadInfo.mFullURL, nullptr, nullptr);
diff --git a/dom/workers/ServiceWorkerManager.cpp b/dom/workers/ServiceWorkerManager.cpp
index a8f191f2e..306ef6b23 100644
--- a/dom/workers/ServiceWorkerManager.cpp
+++ b/dom/workers/ServiceWorkerManager.cpp
@@ -22,7 +22,6 @@
 #include "nsITimer.h"
 #include "nsIUploadChannel2.h"
 #include "nsPIDOMWindow.h"
-#include "nsScriptLoader.h"
 #include "nsServiceManagerUtils.h"
 #include "nsDebug.h"
 #include "nsISupportsPrimitives.h"
@@ -44,6 +43,7 @@
 #include "mozilla/dom/PromiseNativeHandler.h"
 #include "mozilla/dom/Request.h"
 #include "mozilla/dom/RootedDictionary.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/TypedArray.h"
 #include "mozilla/ipc/BackgroundChild.h"
 #include "mozilla/ipc/PBackgroundChild.h"
diff --git a/dom/workers/ServiceWorkerScriptCache.cpp b/dom/workers/ServiceWorkerScriptCache.cpp
index f44bb673c..707b689e8 100644
--- a/dom/workers/ServiceWorkerScriptCache.cpp
+++ b/dom/workers/ServiceWorkerScriptCache.cpp
@@ -11,6 +11,7 @@
 #include "mozilla/dom/cache/Cache.h"
 #include "mozilla/dom/Promise.h"
 #include "mozilla/dom/PromiseWorkerProxy.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/ipc/BackgroundUtils.h"
 #include "mozilla/ipc/PBackgroundSharedTypes.h"
 #include "nsICacheInfoChannel.h"
@@ -23,7 +24,6 @@
 #include "nsIScriptError.h"
 #include "nsContentUtils.h"
 #include "nsNetUtil.h"
-#include "nsScriptLoader.h"
 #include "ServiceWorkerManager.h"
 #include "Workers.h"
 #include "nsStringStream.h"
@@ -801,9 +801,9 @@ CompareNetwork::OnStreamComplete(nsIStreamLoader* aLoader, nsISupports* aContext
   char16_t* buffer = nullptr;
   size_t len = 0;
 
-  rv = nsScriptLoader::ConvertToUTF16(httpChannel, aString, aLen,
-                                      NS_LITERAL_STRING("UTF-8"), nullptr,
-                                      buffer, len);
+  rv = ScriptLoader::ConvertToUTF16(httpChannel, aString, aLen,
+                                    NS_LITERAL_STRING("UTF-8"), nullptr,
+                                    buffer, len);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     mManager->NetworkFinished(rv);
     return rv;
@@ -855,9 +855,9 @@ CompareCache::OnStreamComplete(nsIStreamLoader* aLoader, nsISupports* aContext,
   char16_t* buffer = nullptr;
   size_t len = 0;
 
-  nsresult rv = nsScriptLoader::ConvertToUTF16(nullptr, aString, aLen,
-                                               NS_LITERAL_STRING("UTF-8"),
-                                               nullptr, buffer, len);
+  nsresult rv = ScriptLoader::ConvertToUTF16(nullptr, aString, aLen,
+                                             NS_LITERAL_STRING("UTF-8"),
+                                             nullptr, buffer, len);
   if (NS_WARN_IF(NS_FAILED(rv))) {
     mManager->CacheFinished(rv, false);
     return rv;
diff --git a/dom/worklet/Worklet.cpp b/dom/worklet/Worklet.cpp
index 19a877ea8..1b71916ab 100644
--- a/dom/worklet/Worklet.cpp
+++ b/dom/worklet/Worklet.cpp
@@ -12,11 +12,11 @@
 #include "mozilla/dom/PromiseNativeHandler.h"
 #include "mozilla/dom/RegisterWorkletBindings.h"
 #include "mozilla/dom/Response.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "nsIInputStreamPump.h"
 #include "nsIThreadRetargetableRequest.h"
 #include "nsNetUtil.h"
-#include "nsScriptLoader.h"
 #include "xpcprivate.h"
 
 namespace mozilla {
@@ -171,9 +171,9 @@ public:
     char16_t* scriptTextBuf;
     size_t scriptTextLength;
     nsresult rv =
-      nsScriptLoader::ConvertToUTF16(nullptr, aString, aStringLen,
-                                     NS_LITERAL_STRING("UTF-8"), nullptr,
-                                     scriptTextBuf, scriptTextLength);
+      ScriptLoader::ConvertToUTF16(nullptr, aString, aStringLen,
+                                   NS_LITERAL_STRING("UTF-8"), nullptr,
+                                   scriptTextBuf, scriptTextLength);
     if (NS_WARN_IF(NS_FAILED(rv))) {
       RejectPromises(rv);
       return NS_OK;
diff --git a/dom/xml/nsXMLContentSink.cpp b/dom/xml/nsXMLContentSink.cpp
index 7c9d308fd..daf1dbf27 100644
--- a/dom/xml/nsXMLContentSink.cpp
+++ b/dom/xml/nsXMLContentSink.cpp
@@ -35,7 +35,6 @@
 #include "nsRect.h"
 #include "nsIWebNavigation.h"
 #include "nsIScriptElement.h"
-#include "nsScriptLoader.h"
 #include "nsStyleLinkElement.h"
 #include "nsReadableUtils.h"
 #include "nsUnicharUtils.h"
@@ -62,6 +61,7 @@
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/HTMLTemplateElement.h"
 #include "mozilla/dom/ProcessingInstruction.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
diff --git a/dom/xml/nsXMLFragmentContentSink.cpp b/dom/xml/nsXMLFragmentContentSink.cpp
index 7fa815c84..7d9f86987 100644
--- a/dom/xml/nsXMLFragmentContentSink.cpp
+++ b/dom/xml/nsXMLFragmentContentSink.cpp
@@ -24,10 +24,10 @@
 #include "nsTArray.h"
 #include "nsCycleCollectionParticipant.h"
 #include "nsIDocShell.h"
-#include "nsScriptLoader.h"
 #include "mozilla/css/Loader.h"
 #include "mozilla/dom/DocumentFragment.h"
 #include "mozilla/dom/ProcessingInstruction.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 using namespace mozilla::dom;
 
diff --git a/dom/xslt/xslt/txMozillaXMLOutput.cpp b/dom/xslt/xslt/txMozillaXMLOutput.cpp
index 069413d97..704d8ac11 100644
--- a/dom/xslt/xslt/txMozillaXMLOutput.cpp
+++ b/dom/xslt/xslt/txMozillaXMLOutput.cpp
@@ -7,7 +7,6 @@
 
 #include "nsIDocument.h"
 #include "nsIDocShell.h"
-#include "nsScriptLoader.h"
 #include "nsIDOMDocument.h"
 #include "nsIDOMDocumentType.h"
 #include "nsIScriptElement.h"
@@ -31,6 +30,7 @@
 #include "mozilla/css/Loader.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/EncodingUtils.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "nsContentUtils.h"
 #include "txXMLUtils.h"
 #include "nsContentSink.h"
@@ -230,7 +230,7 @@ txMozillaXMLOutput::endDocument(nsresult aResult)
         MOZ_ASSERT(mDocument->GetReadyStateEnum() ==
                    nsIDocument::READYSTATE_LOADING, "Bad readyState");
         mDocument->SetReadyStateInternal(nsIDocument::READYSTATE_INTERACTIVE);
-        nsScriptLoader* loader = mDocument->ScriptLoader();
+        ScriptLoader* loader = mDocument->ScriptLoader();
         if (loader) {
             loader->ParsingComplete(false);
         }
@@ -416,7 +416,7 @@ txMozillaXMLOutput::startDocument()
     }
 
     if (mCreatingNewDocument) {
-        nsScriptLoader* loader = mDocument->ScriptLoader();
+        ScriptLoader* loader = mDocument->ScriptLoader();
         if (loader) {
             loader->BeginDeferringScripts();
         }
@@ -857,7 +857,7 @@ txMozillaXMLOutput::createResultDocument(const nsSubstring& aName, int32_t aNsID
     }
 
     // Set up script loader of the result document.
-    nsScriptLoader *loader = mDocument->ScriptLoader();
+    ScriptLoader *loader = mDocument->ScriptLoader();
     if (mNotifier) {
         loader->AddObserver(mNotifier);
     }
diff --git a/dom/xul/XULDocument.cpp b/dom/xul/XULDocument.cpp
index 929efc1af..9d5d33636 100644
--- a/dom/xul/XULDocument.cpp
+++ b/dom/xul/XULDocument.cpp
@@ -3336,10 +3336,10 @@ XULDocument::OnStreamComplete(nsIStreamLoader* aLoader,
                                             !mOffThreadCompileStringBuf),
                    "XULDocument can't load multiple scripts at once");
 
-        rv = nsScriptLoader::ConvertToUTF16(channel, string, stringLen,
-                                            EmptyString(), this,
-                                            mOffThreadCompileStringBuf,
-                                            mOffThreadCompileStringLength);
+        rv = ScriptLoader::ConvertToUTF16(channel, string, stringLen,
+                                          EmptyString(), this,
+                                          mOffThreadCompileStringBuf,
+                                          mOffThreadCompileStringLength);
         if (NS_SUCCEEDED(rv)) {
             // Attempt to give ownership of the buffer to the JS engine.  If
             // we hit offthread compilation, however, we will have to take it
diff --git a/dom/xul/XULDocument.h b/dom/xul/XULDocument.h
index 06abb797f..e72edfeed 100644
--- a/dom/xul/XULDocument.h
+++ b/dom/xul/XULDocument.h
@@ -21,13 +21,13 @@
 #include "nsCOMArray.h"
 #include "nsIURI.h"
 #include "nsIXULDocument.h"
-#include "nsScriptLoader.h"
 #include "nsIStreamListener.h"
 #include "nsIStreamLoader.h"
 #include "nsICSSLoaderObserver.h"
 #include "nsIXULStore.h"
 
 #include "mozilla/Attributes.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 #include "js/TracingAPI.h"
 #include "js/TypeDecls.h"
diff --git a/dom/xul/nsXULContentSink.cpp b/dom/xul/nsXULContentSink.cpp
index edeee8728..94560e70d 100644
--- a/dom/xul/nsXULContentSink.cpp
+++ b/dom/xul/nsXULContentSink.cpp
@@ -881,7 +881,7 @@ XULContentSinkImpl::OpenScript(const char16_t** aAttributes,
               isJavaScript = false;
           }
       } else if (key.EqualsLiteral("language")) {
-          // Language is deprecated, and the impl in nsScriptLoader ignores the
+          // Language is deprecated, and the impl in ScriptLoader ignores the
           // various version strings anyway.  So we make no attempt to support
           // languages other than JS for language=
           nsAutoString lang(aAttributes[1]);
diff --git a/js/xpconnect/loader/mozJSSubScriptLoader.cpp b/js/xpconnect/loader/mozJSSubScriptLoader.cpp
index f23e5833a..baf7a9392 100644
--- a/js/xpconnect/loader/mozJSSubScriptLoader.cpp
+++ b/js/xpconnect/loader/mozJSSubScriptLoader.cpp
@@ -15,7 +15,6 @@
 #include "nsNetCID.h"
 #include "nsNetUtil.h"
 #include "nsIFileURL.h"
-#include "nsScriptLoader.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsThreadUtils.h"
 
@@ -26,6 +25,7 @@
 #include "jswrapper.h"
 
 #include "mozilla/dom/Promise.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/ToJSValue.h"
 #include "mozilla/HoldDropJSObjects.h"
 #include "mozilla/scache/StartupCache.h"
@@ -139,8 +139,8 @@ PrepareScript(nsIURI* uri,
         size_t scriptLength = 0;
 
         nsresult rv =
-            nsScriptLoader::ConvertToUTF16(nullptr, reinterpret_cast<const uint8_t*>(buf), len,
-                                           charset, nullptr, scriptBuf, scriptLength);
+            ScriptLoader::ConvertToUTF16(nullptr, reinterpret_cast<const uint8_t*>(buf), len,
+                                         charset, nullptr, scriptBuf, scriptLength);
 
         JS::SourceBufferHolder srcBuf(scriptBuf, scriptLength,
                                       JS::SourceBufferHolder::GiveOwnership);
@@ -826,9 +826,9 @@ ScriptPrecompiler::OnStreamComplete(nsIIncrementalStreamLoader* aLoader,
     // Convert data to char16_t* and prepare to call CompileOffThread.
     nsAutoString hintCharset;
     nsresult rv =
-        nsScriptLoader::ConvertToUTF16(mChannel, aString, aLength,
-                                       hintCharset, nullptr,
-                                       mScriptBuf, mScriptLength);
+        ScriptLoader::ConvertToUTF16(mChannel, aString, aLength,
+                                     hintCharset, nullptr,
+                                     mScriptBuf, mScriptLength);
 
     NS_ENSURE_SUCCESS(rv, NS_OK);
 
diff --git a/js/xpconnect/src/XPCJSContext.cpp b/js/xpconnect/src/XPCJSContext.cpp
index bde949a96..511bc8a98 100644
--- a/js/xpconnect/src/XPCJSContext.cpp
+++ b/js/xpconnect/src/XPCJSContext.cpp
@@ -35,13 +35,13 @@
 #include "nsCCUncollectableMarker.h"
 #include "nsCycleCollectionNoteRootCallback.h"
 #include "nsCycleCollector.h"
-#include "nsScriptLoader.h"
 #include "jsapi.h"
 #include "jsprf.h"
 #include "js/MemoryMetrics.h"
 #include "mozilla/dom/GeneratedAtomList.h"
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/Element.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/dom/WindowBinding.h"
 #include "mozilla/jsipc/CrossProcessObjectWrappers.h"
 #include "mozilla/Atomics.h"
@@ -3035,8 +3035,8 @@ ReadSourceFromFilename(JSContext* cx, const char* filename, char16_t** src, size
         ptr += bytesRead;
     }
 
-    rv = nsScriptLoader::ConvertToUTF16(scriptChannel, buf.get(), rawLen, EmptyString(),
-                                        nullptr, *src, *len);
+    rv = ScriptLoader::ConvertToUTF16(scriptChannel, buf.get(), rawLen, EmptyString(),
+                                      nullptr, *src, *len);
     NS_ENSURE_SUCCESS(rv, rv);
 
     if (!*src)
diff --git a/parser/html/nsHtml5DocumentBuilder.cpp b/parser/html/nsHtml5DocumentBuilder.cpp
index ba8a333c4..aff199a45 100644
--- a/parser/html/nsHtml5DocumentBuilder.cpp
+++ b/parser/html/nsHtml5DocumentBuilder.cpp
@@ -8,8 +8,8 @@
 
 #include "nsIStyleSheetLinkingElement.h"
 #include "nsStyleLinkElement.h"
-#include "nsScriptLoader.h"
 #include "nsIHTMLDocument.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 NS_IMPL_CYCLE_COLLECTION_INHERITED(nsHtml5DocumentBuilder, nsContentSink,
                                    mOwnedElements)
diff --git a/parser/html/nsHtml5OplessBuilder.cpp b/parser/html/nsHtml5OplessBuilder.cpp
index ac1c03f10..65b97ffc7 100644
--- a/parser/html/nsHtml5OplessBuilder.cpp
+++ b/parser/html/nsHtml5OplessBuilder.cpp
@@ -6,8 +6,8 @@
 
 #include "nsHtml5OplessBuilder.h"
 
-#include "nsScriptLoader.h"
 #include "mozilla/css/Loader.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "nsIDocShell.h"
 #include "nsIHTMLDocument.h"
 
diff --git a/parser/html/nsHtml5TreeOpExecutor.cpp b/parser/html/nsHtml5TreeOpExecutor.cpp
index 95f177376..3ed634d0c 100644
--- a/parser/html/nsHtml5TreeOpExecutor.cpp
+++ b/parser/html/nsHtml5TreeOpExecutor.cpp
@@ -7,10 +7,10 @@
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Likely.h"
 #include "mozilla/dom/nsCSPService.h"
+#include "mozilla/dom/ScriptLoader.h"
 
 #include "nsError.h"
 #include "nsHtml5TreeOpExecutor.h"
-#include "nsScriptLoader.h"
 #include "nsIContentViewer.h"
 #include "nsIContentSecurityPolicy.h"
 #include "nsIDocShellTreeItem.h"
diff --git a/parser/html/nsParserUtils.cpp b/parser/html/nsParserUtils.cpp
index 9e0bb8c9e..2085cd149 100644
--- a/parser/html/nsParserUtils.cpp
+++ b/parser/html/nsParserUtils.cpp
@@ -9,7 +9,6 @@
 #include "nsXPCOM.h"
 #include "nsISupportsPrimitives.h"
 #include "nsXPIDLString.h"
-#include "nsScriptLoader.h"
 #include "nsEscape.h"
 #include "nsIParser.h"
 #include "nsIDTD.h"
@@ -36,6 +35,7 @@
 #include "nsTreeSanitizer.h"
 #include "nsHtml5Module.h"
 #include "mozilla/dom/DocumentFragment.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "nsNullPrincipal.h"
 
 #define XHTML_DIV_TAG "div xmlns=\"http://www.w3.org/1999/xhtml\""
@@ -148,7 +148,7 @@ nsParserUtils::ParseFragment(const nsAString& aFragment,
   nsAutoScriptBlockerSuppressNodeRemoved autoBlocker;
 
   // stop scripts
-  RefPtr<nsScriptLoader> loader;
+  RefPtr<ScriptLoader> loader;
   bool scripts_enabled = false;
   if (document) {
     loader = document->ScriptLoader();
diff --git a/parser/htmlparser/nsParser.cpp b/parser/htmlparser/nsParser.cpp
index dd140c553..d1e521750 100644
--- a/parser/htmlparser/nsParser.cpp
+++ b/parser/htmlparser/nsParser.cpp
@@ -28,7 +28,6 @@
 #include "nsIFragmentContentSink.h"
 #include "nsStreamUtils.h"
 #include "nsHTMLTokenizer.h"
-#include "nsScriptLoader.h"
 #include "nsDataHashtable.h"
 #include "nsXPCOMCIDInternal.h"
 #include "nsMimeTypes.h"
@@ -41,6 +40,7 @@
 #include "nsIHTMLContentSink.h"
 
 #include "mozilla/dom/EncodingUtils.h"
+#include "mozilla/dom/ScriptLoader.h"
 #include "mozilla/BinarySearch.h"
 
 using namespace mozilla;