Use downloadToFile option when XHR downloads a Blob

Source/core/loader/WorkerThreadableLoader.cpp

Index: Source/core/loader/WorkerThreadableLoader.cpp
diff --git a/Source/core/loader/WorkerThreadableLoader.cpp b/Source/core/loader/WorkerThreadableLoader.cpp
index d5b77259f171533415ae2b89f1e4ecbedd5825d1..6105fcf2df7191931bd0c2e320e95c0c06491616 100644
--- a/Source/core/loader/WorkerThreadableLoader.cpp
+++ b/Source/core/loader/WorkerThreadableLoader.cpp
@@ -201,6 +201,17 @@ void WorkerThreadableLoader::MainThreadBridge::didReceiveData(const char* data,
     m_loaderProxy.postTaskForModeToWorkerGlobalScope(createCallbackTask(&workerGlobalScopeDidReceiveData, m_workerClientWrapper, vector.release()), m_taskMode);
 }
 
+static void workerGlobalScopeDidDownloadData(ExecutionContext* context, PassRefPtr<ThreadableLoaderClientWrapper> workerClientWrapper, int dataLength)
+{
+    ASSERT_UNUSED(context, context->isWorkerGlobalScope());
+    workerClientWrapper->didDownloadData(dataLength);
+}
+
+void WorkerThreadableLoader::MainThreadBridge::didDownloadData(int dataLength)
+{
+    m_loaderProxy.postTaskForModeToWorkerGlobalScope(createCallbackTask(&workerGlobalScopeDidDownloadData, m_workerClientWrapper, dataLength), m_taskMode);
+}
+
 static void workerGlobalScopeDidReceiveCachedMetadata(ExecutionContext* context, PassRefPtr<ThreadableLoaderClientWrapper> workerClientWrapper, PassOwnPtr<Vector<char> > vectorData)
 {
     ASSERT_UNUSED(context, context->isWorkerGlobalScope());