Reenable optimization on XMLHttpRequest's receive-as-blob functionality

Source/core/xml/XMLHttpRequest.h

 /*
  *  Copyright (C) 2003, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005, 2006 Alexey Proskuryakov <ap@nypop.com>
  *  Copyright (C) 2011 Google Inc. All rights reserved.
  *  Copyright (C) 2012 Intel Corporation
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
@@ skipping 139 matching lines @@
 
 private:
     XMLHttpRequest(ExecutionContext*, PassRefPtr<SecurityOrigin>);
 
     Document* document() const;
     SecurityOrigin* securityOrigin() const;
 
     virtual void didSendData(unsigned long long bytesSent, unsigned long long totalBytesToBeSent) OVERRIDE;
     virtual void didReceiveResponse(unsigned long identifier, const ResourceResponse&) OVERRIDE;
     virtual void didReceiveData(const char* data, int dataLength) OVERRIDE;
+    // When responseType is set to "blob", didDownloadData() is called instead
+    // of didReceiveData().
+    virtual void didDownloadData(int dataLength) OVERRIDE;
     virtual void didFinishLoading(unsigned long identifier, double finishTime) OVERRIDE;
     virtual void didFail(const ResourceError&) OVERRIDE;
     virtual void didFailRedirectCheck() OVERRIDE;
 
     AtomicString responseMIMEType() const;
     bool responseIsXML() const;
 
     bool areMethodAndURLValidForSend();
 
     bool initSend(ExceptionState&);
@@ skipping 58 matching lines @@
 
     OwnPtr<TextResourceDecoder> m_decoder;
 
     ScriptString m_responseText;
     // Used to skip m_responseDocument creation if it's done previously. We need
     // this separate flag since m_responseDocument can be 0 for some cases.
     bool m_createdDocument;
     RefPtrWillBeMember<Document> m_responseDocument;
 
     RefPtr<SharedBuffer> m_binaryResponseBuilder;
+    long long m_downloadedBlobLength;
+
     RefPtr<ArrayBuffer> m_responseArrayBuffer;
 
     bool m_error;
 
     bool m_uploadEventsAllowed;
     bool m_uploadComplete;
 
     bool m_sameOriginRequest;
 
     // Used for onprogress tracking
@@ skipping 10 matching lines @@
 
     // An enum corresponding to the allowed string values for the responseType attribute.
     ResponseTypeCode m_responseTypeCode;
     AsyncMethodRunner<XMLHttpRequest> m_dropProtectionRunner;
     RefPtr<SecurityOrigin> m_securityOrigin;
 };
 
 } // namespace WebCore
 
 #endif // XMLHttpRequest_h