[Fetch] Support various operations after reading data partially.

Source/modules/serviceworkers/Cache.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/serviceworkers/Cache.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "bindings/core/v8/ScriptState.h"
@@ skipping 354 matching lines @@
         return ScriptPromise::reject(scriptState, V8ThrowException::createTypeError(scriptState->isolate(), "Response body is already used"));
 
     if (request->hasBody())
         request->setBodyUsed();
     if (response->hasBody())
         response->setBodyUsed();
 
     RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
     const ScriptPromise promise = resolver->promise();
     if (BodyStreamBuffer* buffer = response->internalBuffer()) {
-        if (buffer == response->buffer() && response->streamAccessed()) {
-            bool dataLost = false;
-            buffer = response->createDrainingStream(&dataLost);
-            if (dataLost) {
-                resolver->reject(DOMException::create(NotSupportedError, "Storing the Response which .body is partially read is not supported."));
-                return promise;
-            }
-        }
+        if (buffer == response->buffer() && response->streamAccessed())
+            buffer = response->createDrainingStream();
         // If the response body type is stream, read the all data and create the
         // blob handle and dispatch the put batch asynchronously.
         buffer->readAllAndCreateBlobHandle(response->internalContentTypeForBuffer(), new AsyncPutBatch(resolver, this, request, response));
         return promise;
     }
     WebVector<WebServiceWorkerCache::BatchOperation> batchOperations(size_t(1));
     batchOperations[0].operationType = WebServiceWorkerCache::OperationTypePut;
     request->populateWebServiceWorkerRequest(batchOperations[0].request);
     response->populateWebServiceWorkerResponse(batchOperations[0].response);
 
@@ skipping 19 matching lines @@
     m_webCache->dispatchKeys(new CacheWithRequestsCallbacks(resolver), 0, toWebQueryParams(options));
     return promise;
 }
 
 WebServiceWorkerCache* Cache::webCache() const
 {
     return m_webCache.get();
 }
 
 } // namespace blink