Make data: urls always parse async

Source/core/html/parser/HTMLParserOptions.cpp

 /*
  * Copyright (C) 2013 Google, Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 23 matching lines @@
 
 namespace WebCore {
 
 HTMLParserOptions::HTMLParserOptions(Document* document)
 {
     LocalFrame* frame = document ? document->frame() : 0;
     scriptEnabled = frame && frame->script().canExecuteScripts(NotAboutToExecuteScript);
     pluginsEnabled = frame && frame->loader().allowPlugins(NotAboutToInstantiatePlugin);
 
     Settings* settings = document ? document->settings() : 0;
-    // We force the main-thread parser for about:blank, javascript: and data: urls for compatibility
-    // with historical synchronous loading/parsing behavior of those schemes.
+    // We force the main-thread parser for about:blank and javascript: for compatibility
+    // with historical synchronous loading/parsing behavior.
+    // FIXME: Gecko does not load javascript: urls synchronously, why do we?
+    // See LayoutTests/loader/iframe-sync-loads.html
     // FIXME: Use isAboutBlankURL() instead of protocolIsAbout() to not include about:srcdoc.
-    useThreading = settings && settings->threadedHTMLParser() && !document->url().protocolIsAbout()
-        && (settings->useThreadedHTMLParserForDataURLs() || !document->url().protocolIsData());
+    useThreading = settings && settings->threadedHTMLParser() && !document->url().protocolIsAbout();
 }
 
 }