Make WorkerScriptLoader back to RefCounted class

Source/web/WebSharedWorkerImpl.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 135 matching lines @@
     OwnPtr<WorkerInspectorProxy> m_workerInspectorProxy;
 
     RefPtr<WorkerThread> m_workerThread;
 
     WebSharedWorkerClient* m_client;
 
     bool m_pauseWorkerContextOnStart;
     bool m_isPausedOnStart;
 
     // Kept around only while main script loading is ongoing.
-    OwnPtr<WorkerScriptLoader> m_mainScriptLoader;
+    RefPtr<WorkerScriptLoader> m_mainScriptLoader;
 
     RefPtr<WorkerLoaderProxy> m_loaderProxy;
 
     WebURL m_url;
     WebString m_name;
 };
 
 } // namespace blink
 
 #endif // WebSharedWorkerImpl_h