[Fetch] Support various operations after reading data partially.

Source/modules/serviceworkers/RespondWithObserver.cpp

Index: Source/modules/serviceworkers/RespondWithObserver.cpp
diff --git a/Source/modules/serviceworkers/RespondWithObserver.cpp b/Source/modules/serviceworkers/RespondWithObserver.cpp
index 37ffa42afa8c3e1017836fe3b292afbb20041c01..4de283392276d40eae786814c327d8288b5134a5 100644
--- a/Source/modules/serviceworkers/RespondWithObserver.cpp
+++ b/Source/modules/serviceworkers/RespondWithObserver.cpp
@@ -204,13 +204,7 @@ void RespondWithObserver::responseWasFulfilled(const ScriptValue& value)
     response->setBodyUsed();
     if (BodyStreamBuffer* buffer = response->internalBuffer()) {
         if (buffer == response->buffer() && response->streamAccessed()) {

[horo, 2015/03/20 02:28:54]

nit: we can remove brackets.

[yhirano, 2015/03/20 03:24:49]

Done.

-            bool dataLost = false;
-            buffer = response->createDrainingStream(&dataLost);
-            if (dataLost) {
-                executionContext()->addConsoleMessage(ConsoleMessage::create(JSMessageSource, ErrorMessageLevel, "Returning the stream accessed Response to the page is not supported."));
-                responseWasRejected();
-                return;
-            }
+            buffer = response->createDrainingStream();
         }
         WebServiceWorkerResponse webResponse;
         response->populateWebServiceWorkerResponse(webResponse);