Use downloadToFile option when XHR downloads a Blob

Source/core/fetch/FetchContext.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:
  *
  *     * 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 55 matching lines @@
 }
 
 void FetchContext::dispatchDidReceiveResponse(DocumentLoader*, unsigned long, const ResourceResponse&, ResourceLoader*)
 {
 }
 
 void FetchContext::dispatchDidReceiveData(DocumentLoader*, unsigned long, const char*, int, int)
 {
 }
 
+void FetchContext::dispatchDidDownloadData(DocumentLoader*, unsigned long, int, int)
+{
+}
+
 void FetchContext::dispatchDidFinishLoading(DocumentLoader*, unsigned long, double)
 {
 }
 
 void FetchContext::dispatchDidFail(DocumentLoader*, unsigned long, const ResourceError&)
 {
 }
 
 void FetchContext::sendRemainingDelegateMessages(DocumentLoader*, unsigned long, const ResourceResponse&, const char*, int, int, const ResourceError&)
 {
 }
 
 } // namespace WebCore