Cleanup FrameLoader::opener() to return a Frame*.

Source/core/frame/LocalDOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 1258 matching lines @@
         return 0;
 
     return m_frame->domWindow();
 }
 
 LocalDOMWindow* LocalDOMWindow::opener() const
 {
     if (!m_frame)
         return 0;
 
-    LocalFrame* opener = m_frame->loader().opener();
+    Frame* opener = m_frame->loader().opener();
     if (!opener)
         return 0;
 
     return opener->domWindow();
 }
 
 LocalDOMWindow* LocalDOMWindow::parent() const
 {
     if (!m_frame)
         return 0;
@@ skipping 624 matching lines @@
     visitor->trace(m_applicationCache);
     visitor->trace(m_performance);
     visitor->trace(m_css);
     visitor->trace(m_eventQueue);
     WillBeHeapSupplementable<LocalDOMWindow>::trace(visitor);
     EventTargetWithInlineData::trace(visitor);
     LifecycleContext<LocalDOMWindow>::trace(visitor);
 }
 
 } // namespace blink