Bug 1276477, make document update less malloc heavy, r=baku

--HG--
extra : rebase_source : 5cf067fb8a874c144fcf7c1f85210a944ed75878

dom/base/nsContentUtils.cpp

@@ -250,7 +250,7 @@ nsIBidiKeyboard *nsContentUtils::sBidiKeyboard = nullptr;
 uint32_t nsContentUtils::sScriptBlockerCount = 0;
 uint32_t nsContentUtils::sDOMNodeRemovedSuppressCount = 0;
 uint32_t nsContentUtils::sMicroTaskLevel = 0;
-nsTArray< nsCOMPtr<nsIRunnable> >* nsContentUtils::sBlockedScriptRunners = nullptr;
+AutoTArray<nsCOMPtr<nsIRunnable>, 8>* nsContentUtils::sBlockedScriptRunners = nullptr;
 uint32_t nsContentUtils::sRunnersCountAtFirstBlocker = 0;
 nsIInterfaceRequestor* nsContentUtils::sSameOriginChecker = nullptr;
 
@@ -534,7 +534,7 @@ nsContentUtils::Init()
     RegisterStrongMemoryReporter(new DOMEventListenerManagersHashReporter());
   }
 
-  sBlockedScriptRunners = new nsTArray< nsCOMPtr<nsIRunnable> >;
+  sBlockedScriptRunners = new AutoTArray<nsCOMPtr<nsIRunnable>, 8>;
 
   Preferences::AddBoolVarCache(&sAllowXULXBL_for_file,
                                "dom.allow_XUL_XBL_for_file");

dom/base/nsContentUtils.h

@@ -2658,7 +2658,7 @@ private:
   static uint32_t sDOMNodeRemovedSuppressCount;
   static uint32_t sMicroTaskLevel;
   // Not an nsCOMArray because removing elements from those is slower
-  static nsTArray< nsCOMPtr<nsIRunnable> >* sBlockedScriptRunners;
+  static AutoTArray<nsCOMPtr<nsIRunnable>, 8>* sBlockedScriptRunners;
   static uint32_t sRunnersCountAtFirstBlocker;
   static uint32_t sScriptBlockerCountWhereRunnersPrevented;
 

dom/base/nsDocument.cpp

@@ -1809,6 +1809,13 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INTERNAL(nsDocument)
     return NS_SUCCESS_INTERRUPTED_TRAVERSE;
   }
 
+  if (tmp->mMaybeEndOutermostXBLUpdateRunner) {
+    // The cached runnable keeps a reference to the document object..
+    NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb,
+                                       "mMaybeEndOutermostXBLUpdateRunner.mObj");
+    cb.NoteXPCOMChild(ToSupports(tmp));
+  }
+
   for (auto iter = tmp->mIdentifierMap.ConstIter(); !iter.Done();
        iter.Next()) {
     iter.Get()->Traverse(&cb);
@@ -1959,6 +1966,7 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDocument)
   tmp->mCachedRootElement = nullptr; // Avoid a dangling pointer
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDisplayDocument)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mFirstBaseNodeWithHref)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mMaybeEndOutermostXBLUpdateRunner)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDOMImplementation)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mImageMaps)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mCachedEncoder)
@@ -4981,8 +4989,11 @@ nsDocument::MaybeEndOutermostXBLUpdate()
       mInXBLUpdate = false;
       BindingManager()->EndOutermostUpdate();
     } else if (!mInDestructor) {
-      nsContentUtils::AddScriptRunner(
-        NewRunnableMethod(this, &nsDocument::MaybeEndOutermostXBLUpdate));
+      if (!mMaybeEndOutermostXBLUpdateRunner) {
+        mMaybeEndOutermostXBLUpdateRunner =
+          NewRunnableMethod(this, &nsDocument::MaybeEndOutermostXBLUpdate);
+      }
+      nsContentUtils::AddScriptRunner(mMaybeEndOutermostXBLUpdateRunner);
     }
   }
 }

dom/base/nsDocument.h

@@ -1789,6 +1789,8 @@ private:
   nsTArray<nsCOMPtr<nsIRunnable> > mFrameLoaderFinalizers;
   RefPtr<nsRunnableMethod<nsDocument> > mFrameLoaderRunner;
 
+  nsCOMPtr<nsIRunnable> mMaybeEndOutermostXBLUpdateRunner;
+
   nsRevocableEventPtr<nsRunnableMethod<nsDocument, void, false> >
     mPendingTitleChangeEvent;