[Fetch] Response.clone should tee the body stream.

Source/modules/fetch/Request.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "modules/fetch/Request.h"
 
 #include "bindings/core/v8/Dictionary.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExecutionContext.h"
@@ skipping 33 matching lines @@
 Request* Request::createRequestWithRequestOrString(ExecutionContext* context, Request* inputRequest, const String& inputString, const RequestInit& init, ExceptionState& exceptionState)
 {
     // "1. If input is a Request object, run these substeps:"
     if (inputRequest) {
         // "1. If input's used flag is set, throw a TypeError."
         if (inputRequest->bodyUsed()) {
             exceptionState.throwTypeError("Cannot construct a Request with a Request object that has already been used.");
             return 0;
         }
         // "2. Set input's used flag."
-        inputRequest->setBodyUsed();
+        inputRequest->lockBody(PassBody);
     }
 
     // "2. Let |request| be |input|'s associated request, if |input| is a
     // Request object, and a new request otherwise."
     // "3. Set |request| to a new request whose url is |request|'s url, method
     // is |request|'s method, header list is a copy of |request|'s header list,
     // unsafe request flag is set, body is |request|'s body, client is entry
     // settings object, origin is entry settings object's origin, force Origin
     // header flag is set, same-origin data URL flag is set, referrer is client,
     // context is fetch, mode is |request|'s mode, credentials mode is
@@ skipping 275 matching lines @@
     Headers* headers = Headers::create(request->headerList());
     headers->setGuard(m_headers->guard());
     Request* r = new Request(executionContext(), request, headers);
     r->suspendIfNeeded();
     return r;
 }
 
 FetchRequestData* Request::passRequestData()
 {
     ASSERT(!bodyUsed());
-    setBodyUsed();
+    lockBody(PassBody);
     return m_request->pass();
 }
 
 void Request::populateWebServiceWorkerRequest(WebServiceWorkerRequest& webRequest) const
 {
     webRequest.setMethod(method());
     // This strips off the fragment part.
     webRequest.setURL(url());
 
     const FetchHeaderList* headerList = m_headers->headerList();
@@ skipping 34 matching lines @@
 }
 
 DEFINE_TRACE(Request)
 {
     Body::trace(visitor);
     visitor->trace(m_request);
     visitor->trace(m_headers);
 }
 
 } // namespace blink