[Mypal] Account for users disabling off-line and memory caching.

application/palemoon/base/content/browser.js

@@ -5893,7 +5893,12 @@ var OfflineApps = {
     var cacheService = Cc["@mozilla.org/network/application-cache-service;1"]
                          .getService(Ci.nsIApplicationCacheService);
     if (!groups) {
+      try {
         groups = cacheService.getGroups();
+      } catch(ex) {
+        // Cache disabled.
+        return 0;
+      }
     }
 
     var usage = 0;

application/palemoon/components/preferences/advanced.js

@@ -286,7 +286,11 @@ var gAdvancedPane = {
       Components.classes["@mozilla.org/netwerk/cache-storage-service;1"]
                 .getService(Components.interfaces.nsICacheStorageService);
     var storage = cacheService.appCacheStorage(LoadContextInfo.default, null);
+    try {
       storage.asyncVisitStorage(visitor, false);
+    } catch(ex) {
+      // Service unavailable: user most likely crippled the cache.
+    }
   },
 
   updateCacheSizeUI: function(smartSizeEnabled)
@@ -396,8 +400,14 @@ var gAdvancedPane = {
   {
     var cacheService = Components.classes["@mozilla.org/network/application-cache-service;1"].
                        getService(Components.interfaces.nsIApplicationCacheService);
-    if (!groups)
+    if (!groups) {
+      try {
         groups = cacheService.getGroups();
+      } catch(ex) {
+        // Cache disabled.
+        return 0;
+      }
+    }
 
     var ios = Components.classes["@mozilla.org/network/io-service;1"].
               getService(Components.interfaces.nsIIOService);
@@ -429,6 +439,8 @@ var gAdvancedPane = {
 
     var cacheService = Components.classes["@mozilla.org/network/application-cache-service;1"].
                        getService(Components.interfaces.nsIApplicationCacheService);
+    
+    try {
       var groups = cacheService.getGroups();
 
       var bundle = document.getElementById("bundlePreferences");
@@ -451,6 +463,10 @@ var gAdvancedPane = {
           list.appendChild(row);
         }
       }
+    } catch(ex) {
+        // Cache service unavailable/errored, off-line app cache is disabled or 0
+        // Do nothing, just leave the box blank.
+    }
   },
 
   offlineAppSelected: function()