Make multipart image documents work again.

Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 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.
@@ skipping 525 matching lines @@
 void DocumentLoader::clearRedirectChain()
 {
     m_redirectChain.clear();
 }
 
 void DocumentLoader::appendRedirect(const KURL& url)
 {
     m_redirectChain.append(url);
 }
 
+bool DocumentLoader::loadingMultipartContent() const
+{
+    return mainResourceLoader() ? mainResourceLoader()->loadingMultipartContent() : false;
+}
+
 void DocumentLoader::detachFromFrame()
 {
     ASSERT(m_frame);
     RefPtrWillBeRawPtr<LocalFrame> protectFrame(m_frame);
     RefPtr<DocumentLoader> protectLoader(this);
 
     // It never makes sense to have a document loader that is detached from its
     // frame have any loads active, so go ahead and kill all the loads.
     stopLoading();
 
@@ skipping 211 matching lines @@
 // This is only called by FrameLoader::replaceDocumentWhileExecutingJavaScriptURL()
 void DocumentLoader::replaceDocumentWhileExecutingJavaScriptURL(const DocumentInit& init, const String& source, Document* ownerDocument)
 {
     m_writer = createWriterFor(ownerDocument, init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true, ForceSynchronousParsing);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 } // namespace blink