Make XHR use the background HTML parser

Source/core/inspector/DOMPatchSupport.cpp

 /*
  * Copyright (C) 2012 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 79 matching lines @@
     else if (document().isXMLDocument())
         newDocument = XMLDocument::create();
 
     ASSERT(newDocument);
     newDocument->setContextFeatures(document().contextFeatures());
     RefPtrWillBeRawPtr<DocumentParser> parser = nullptr;
     if (document().isHTMLDocument())
         parser = HTMLDocumentParser::create(toHTMLDocument(*newDocument), false);
     else
         parser = XMLDocumentParser::create(*newDocument, 0);
+    parser->pinToMainThread();

[eseidel, 2014/09/09 22:18:20]

This shouldn't be necessary with insert(), but seems like a good idea
regardless.

     parser->insert(markup); // Use insert() so that the parser will not yield.
     parser->finish();
     parser->detach();
 
     OwnPtr<Digest> oldInfo = createDigest(document().documentElement(), 0);
     OwnPtr<Digest> newInfo = createDigest(newDocument->documentElement(), &m_unusedNodesMap);
 
     if (!innerPatchNode(oldInfo.get(), newInfo.get(), IGNORE_EXCEPTION)) {
         // Fall back to rewrite.
         document().write(markup);
@@ skipping 396 matching lines @@
 void DOMPatchSupport::dumpMap(const ResultMap& map, const String& name)
 {
     fprintf(stderr, "\n\n");
     for (size_t i = 0; i < map.size(); ++i)
         fprintf(stderr, "%s[%lu]: %s (%p) - [%lu]\n", name.utf8().data(), i, map[i].first ? nodeName(map[i].first->m_node).utf8().data() : "", map[i].first, map[i].second);
 }
 #endif
 
 } // namespace blink