Let FullscreenElementStack methods take references where possible

Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 3435 matching lines @@
     // controller and so it will clear itself on destruction.
 #if !ENABLE(OILPAN)
     if (m_mediaController)
         m_mediaController->clearExecutionContext();
 #endif
     ActiveDOMObject::contextDestroyed();
 }
 
 bool HTMLMediaElement::isFullscreen() const
 {
-    return FullscreenElementStack::isActiveFullScreenElement(this);
+    return FullscreenElementStack::isActiveFullScreenElement(*this);
 }
 
 void HTMLMediaElement::enterFullscreen()
 {
     WTF_LOG(Media, "HTMLMediaElement::enterFullscreen");
 
-    FullscreenElementStack::from(document()).requestFullScreenForElement(this, 0, FullscreenElementStack::ExemptIFrameAllowFullScreenRequirement);
+    FullscreenElementStack::from(document()).requestFullScreenForElement(*this, 0, FullscreenElementStack::ExemptIFrameAllowFullScreenRequirement);
 }
 
 void HTMLMediaElement::exitFullscreen()
 {
     WTF_LOG(Media, "HTMLMediaElement::exitFullscreen");
 
     FullscreenElementStack::from(document()).webkitCancelFullScreen();
 }
 
 void HTMLMediaElement::didBecomeFullscreenElement()
@@ skipping 487 matching lines @@
 
 #if ENABLE(WEB_AUDIO)
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)
 {
     if (!visitor->isAlive(m_audioSourceNode) && audioSourceProvider())
         audioSourceProvider()->setClient(0);
 }
 #endif
 
 }