DOMDataStore should be cleared when shutting down worker threads

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index ef3933d36015a2b3464cf63f89af2d8dbd7c6d10..07b94c6ac1c4c91ff76a5e26a9ca235b0b7247fc 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -1443,10 +1443,10 @@ void FrameLoader::dispatchDidClearWindowObjectsInAllWorlds()
         page->inspectorController().didClearWindowObjectInMainWorld(m_frame);
     InspectorInstrumentation::didClearWindowObjectInMainWorld(m_frame);
 
-    Vector<RefPtr<DOMWrapperWorld> > worlds;
+    Vector<DOMWrapperWorld*> worlds;
     DOMWrapperWorld::allWorldsInMainThread(worlds);
     for (size_t i = 0; i < worlds.size(); ++i)
-        m_client->dispatchDidClearWindowObjectInWorld(worlds[i].get());
+        m_client->dispatchDidClearWindowObjectInWorld(worlds[i]);
 }
 
 void FrameLoader::dispatchDidClearWindowObjectInWorld(DOMWrapperWorld* world)