[XMLHttpRequest] Stop throwing for network error in async mode

Source/core/xmlhttprequest/XMLHttpRequest.cpp

 /*
  *  Copyright (C) 2004, 2006, 2008 Apple Inc. All rights reserved.
  *  Copyright (C) 2005-2007 Alexey Proskuryakov <ap@webkit.org>
  *  Copyright (C) 2007, 2008 Julien Chaffraix <jchaffraix@webkit.org>
  *  Copyright (C) 2008, 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
@@ skipping 1049 matching lines @@
     if (m_async) {
         UseCounter::count(&executionContext, UseCounter::XMLHttpRequestAsynchronous);
         if (m_upload)
             request.setReportUploadProgress(true);
 
         // ThreadableLoader::create can return null here, for example if we're no longer attached to a page.
         // This is true while running onunload handlers.
         // FIXME: Maybe we need to be able to send XMLHttpRequests from onunload, <http://bugs.webkit.org/show_bug.cgi?id=10904>.
         // FIXME: Maybe create() can return null for other reasons too?
         ASSERT(!m_loader);
         m_loader = ThreadableLoader::create(executionContext, this, request, options, resourceLoaderOptions);

[sof, 2015/07/12 13:34:48]

Given that async will now no longer throw, I think the code would read better if
you simply "return;" here.

[tyoshino (SeeGerritForStatus), 2015/07/14 07:00:05]

Done.

     } else {
         // Use count for XHR synchronous requests.
         UseCounter::count(&executionContext, UseCounter::XMLHttpRequestSynchronous);
         ThreadableLoader::loadResourceSynchronously(executionContext, request, *this, options, resourceLoaderOptions);
+
+        if (!m_exceptionCode && m_error)
+            m_exceptionCode = NetworkError;
+        if (m_exceptionCode)
+            exceptionState.throwDOMException(m_exceptionCode, "Failed to load '" + m_url.elidedString() + "'.");
     }
-
-    if (!m_exceptionCode && m_error)
-        m_exceptionCode = NetworkError;
-    if (m_exceptionCode)
-        exceptionState.throwDOMException(m_exceptionCode, "Failed to load '" + m_url.elidedString() + "'.");
 }
 
 void XMLHttpRequest::abort()
 {
     WTF_LOG(Network, "XMLHttpRequest %p abort()", this);
 
     // internalAbort() clears |m_loader|. Compute |sendFlag| now.
     //
     // |sendFlag| corresponds to "the send() flag" defined in the XHR spec.
     //
@@ skipping 771 matching lines @@
     visitor->trace(m_responseDocumentParser);
     visitor->trace(m_progressEventThrottle);
     visitor->trace(m_upload);
     visitor->trace(m_blobLoader);
     XMLHttpRequestEventTarget::trace(visitor);
     DocumentParserClient::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink