Revert of [XMLHttpRequest] Stop throwing for network error in async mode

Source/core/xmlhttprequest/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 181 matching lines @@
     bool responseIsXML() const;
     bool responseIsHTML() const;
 
     PassOwnPtr<TextResourceDecoder> createDecoder() const;
 
     void initResponseDocument();
     void parseDocumentChunk(const char* data, unsigned dataLength);
 
     bool areMethodAndURLValidForSend();
 
-    void throwForLoadFailureIfNeeded(ExceptionState&, const String&);
-
     bool initSend(ExceptionState&);
     void sendBytesData(const void*, size_t, ExceptionState&);
     void send(Document*, ExceptionState&);
     void send(const String&, ExceptionState&);
     void send(Blob*, ExceptionState&);
     void send(DOMFormData*, ExceptionState&);
     void send(DOMArrayBuffer*, ExceptionState&);
     void send(DOMArrayBufferView*, ExceptionState&);
 
     const AtomicString& getRequestHeader(const AtomicString& name) const;
@@ skipping 101 matching lines @@
     bool m_sameOriginRequest;
     // True iff the ongoing resource loading is using the downloadToFile
     // option.
     bool m_downloadingToFile;
     bool m_responseTextOverflow;
 };
 
 } // namespace blink
 
 #endif // XMLHttpRequest_h