Make multipart image documents work again.

Source/core/fetch/ResourceLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
  *           (C) 2007 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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 44 matching lines @@
 {
     RefPtrWillBeRawPtr<ResourceLoader> loader(adoptRefWillBeNoop(new ResourceLoader(fetcher, resource, options)));
     loader->init(request);
     return loader.release();
 }
 
 ResourceLoader::ResourceLoader(ResourceFetcher* fetcher, Resource* resource, const ResourceLoaderOptions& options)
     : m_fetcher(fetcher)
     , m_notifiedLoadComplete(false)
     , m_defersLoading(fetcher->defersLoading())
+    , m_loadingMultipartContent(false)
     , m_options(options)
     , m_resource(resource)
     , m_state(Initialized)
     , m_connectionState(ConnectionStateNew)
 {
 }
 
 ResourceLoader::~ResourceLoader()
 {
     ASSERT(m_state == Terminated);
@@ skipping 294 matching lines @@
     RefPtrWillBeRawPtr<ResourceLoader> protect(this);
     m_resource->responseReceived(resourceResponse, handle.release());
     if (m_state == Terminated)
         return;
 
     m_fetcher->didReceiveResponse(m_resource, resourceResponse);
     if (m_state == Terminated)
         return;
 
     if (response.toResourceResponse().isMultipart()) {
-        if (!m_resource->isImage()) {
+        // We only support multipart for images, though the image may be loaded
+        // as a main resource that we end up displaying through an ImageDocument.
+        if (!m_resource->isImage() && m_resource->type() != Resource::MainResource) {
             cancel();
             return;
         }
+        m_loadingMultipartContent = true;
     } else if (isMultipartPayload) {
         // Since a subresource loader does not load multipart sections progressively, data was delivered to the loader all at once.
         // After the first multipart section is complete, signal to delegates that this load is "finished"
         m_fetcher->subresourceLoaderFinishedLoadingOnePart(this);
         didFinishLoadingOnePart(0, WebURLLoaderClient::kUnknownEncodedDataLength);
     }
     if (m_state == Terminated)
         return;
 
     if (m_resource->response().httpStatusCode() < 400 || m_resource->shouldIgnoreHTTPStatusCodeErrors())
@@ skipping 139 matching lines @@
     didFinishLoading(0, monotonicallyIncreasingTime(), encodedDataLength);
 }
 
 ResourceRequest& ResourceLoader::applyOptions(ResourceRequest& request) const
 {
     request.setAllowStoredCredentials(m_options.allowCredentials == AllowStoredCredentials);
     return request;
 }
 
 }