Adds a CancellableTaskFactory and exposes postLoadingTasks to Blink

Source/core/html/parser/BackgroundHTMLParser.cpp

Index: Source/core/html/parser/BackgroundHTMLParser.cpp
diff --git a/Source/core/html/parser/BackgroundHTMLParser.cpp b/Source/core/html/parser/BackgroundHTMLParser.cpp
index 0b2d141e3020c4029dce6e62956a2517c462dd8b..c650b14b1a6ae250f0144692b848b464a439a258 100644
--- a/Source/core/html/parser/BackgroundHTMLParser.cpp
+++ b/Source/core/html/parser/BackgroundHTMLParser.cpp
@@ -29,6 +29,7 @@
 #include "core/html/parser/HTMLDocumentParser.h"
 #include "core/html/parser/TextResourceDecoder.h"
 #include "core/html/parser/XSSAuditor.h"
+#include "platform/scheduler/Scheduler.h"
 #include "wtf/MainThread.h"
 #include "wtf/text/TextPosition.h"
 
@@ -267,7 +268,9 @@ void BackgroundHTMLParser::sendTokensToMainThread()
     chunk->tokens = m_pendingTokens.release();
     chunk->startingScript = m_startingScript;
     m_startingScript = false;
-    callOnMainThread(bind(&HTMLDocumentParser::didReceiveParsedChunkFromBackgroundParser, m_parser, chunk.release()));
+
+    Scheduler::shared()->postLoadingTask(
+        FROM_HERE, bind(&HTMLDocumentParser::didReceiveParsedChunkFromBackgroundParser, m_parser, chunk.release()));
 
     m_pendingTokens = adoptPtr(new CompactHTMLTokenStream);
 }