Capture delayed events and cancel as necessary.

dom/base/nsGlobalWindow.cpp

@@ -9335,7 +9335,7 @@ nsGlobalWindow::EnterModalState()
 
     topWin->mSuspendedDoc = topDoc;
     if (topDoc) {
-      topDoc->SuppressEventHandling(nsIDocument::eAnimationsOnly);
+      topDoc->SuppressEventHandling(nsIDocument::eEvents);
     }
 
     nsGlobalWindow* inner = topWin->GetCurrentInnerWindowInternal();
@@ -9372,7 +9372,7 @@ nsGlobalWindow::LeaveModalState()
 
     if (topWin->mSuspendedDoc) {
       nsCOMPtr<nsIDocument> currentDoc = topWin->GetExtantDoc();
-      topWin->mSuspendedDoc->UnsuppressEventHandlingAndFireEvents(nsIDocument::eAnimationsOnly,
+      topWin->mSuspendedDoc->UnsuppressEventHandlingAndFireEvents(nsIDocument::eEvents,
                                                                   currentDoc == topWin->mSuspendedDoc);
       topWin->mSuspendedDoc = nullptr;
     }

layout/base/nsPresShell.cpp

@@ -8192,6 +8192,9 @@ PresShell::HandleEventInternal(WidgetEvent* aEvent,
           }
         }
       }
+      if (aEvent->mMessage == eKeyDown) {
+        mIsLastKeyDownCanceled = aEvent->mFlags.mDefaultPrevented;
+      }
       break;
     }
     case eMouseUp:
@@ -8981,6 +8984,9 @@ PresShell::FireOrClearDelayedEvents(bool aFireEvents)
            !doc->EventHandlingSuppressed()) {
       nsAutoPtr<DelayedEvent> ev(mDelayedEvents[0].forget());
       mDelayedEvents.RemoveElementAt(0);
+      if (ev->IsKeyPressEvent() && mIsLastKeyDownCanceled) {
+        continue;
+      }
       ev->Dispatch();
     }
     if (!doc->EventHandlingSuppressed()) {
@@ -9775,6 +9781,12 @@ PresShell::DelayedKeyEvent::DelayedKeyEvent(WidgetKeyboardEvent* aEvent) :
   mEvent = keyEvent;
 }
 
+bool
+PresShell::DelayedKeyEvent::IsKeyPressEvent()
+{
+  return mEvent->mMessage == eKeyPress;
+}
+
 // Start of DEBUG only code
 
 #ifdef DEBUG

layout/base/nsPresShell.h

@@ -617,6 +617,7 @@ protected:
   public:
     virtual ~DelayedEvent() { }
     virtual void Dispatch() { }
+    virtual bool IsKeyPressEvent() { return false; }
   };
 
   class DelayedInputEvent : public DelayedEvent
@@ -641,6 +642,7 @@ protected:
   {
   public:
     explicit DelayedKeyEvent(mozilla::WidgetKeyboardEvent* aEvent);
+    virtual bool IsKeyPressEvent() override;
   };
 
   // Check if aEvent is a mouse event and record the mouse location for later
@@ -951,6 +953,8 @@ protected:
   // Whether the widget has received a paint message yet.
   bool                      mHasReceivedPaintMessage : 1;
 
+  bool                      mIsLastKeyDownCanceled : 1;
+
   static bool               sDisableNonTestMouseEvents;
 };
 

toolkit/components/passwordmgr/test/subtst_master_pass.html

@@ -2,11 +2,6 @@
 This form triggers a MP and gets filled in.<br>
 <form>
 Username: <input type="text"     id="userfield" name="u"><br>
-Password: <input type="password" id="passfield" name="p"><br>
+Password: <input type="password" id="passfield" name="p"
-<script>
+                 oninput="parent.postMessage('filled', '*');"><br>
-    // Only notify when we fill in the password field.
-    document.getElementById("passfield").addEventListener("input", function() {
-        parent.postMessage("filled", "*");
-    });
-</script>
 </form>