[Fetch API] Fix ScriptState leak in Fetch API unittests.

Source/modules/fetch/DataConsumerHandleTestUtil.cpp

 // Copyright 2015 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/DataConsumerHandleTestUtil.h"
 
 #include "bindings/core/v8/DOMWrapperWorld.h"
 
 namespace blink {
@@ skipping 26 matching lines @@
     }
     if (m_initializationPolicy >= WithExecutionContext) {
         m_executionContext = adoptRefWillBeNoop(new NullExecutionContext());
     }
     m_waitableEvent->signal();
 }
 
 void DataConsumerHandleTestUtil::Thread::shutdown()
 {
     m_executionContext = nullptr;
+    if (m_scriptState) {
+        m_scriptState->disposePerContextData();
+    }
     m_scriptState = nullptr;
     m_thread->shutdown();
     if (m_isolateHolder) {
         isolate()->Exit();
         m_isolateHolder = nullptr;
     }
     m_waitableEvent->signal();
 }
 
 class DataConsumerHandleTestUtil::ReplayingHandle::ReaderImpl final : public Reader {
@@ skipping 238 matching lines @@
     m_reader = nullptr;
 }
 
 void DataConsumerHandleTestUtil::HandleTwoPhaseReader::runOnFinishedReading(PassOwnPtr<HandleReadResult> result)
 {
     ASSERT(m_onFinishedReading);
     (*m_onFinishedReading.release())(result);
 }
 
 } // namespace blink