Revert 111028 - Support W3C Full Screen API proposal

Source/WebKit2/WebProcess/FullScreen/WebFullScreenManager.cpp

 /*
  * Copyright (C) 2011 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 83 matching lines @@
 void WebFullScreenManager::enterFullScreenForElement(WebCore::Element* element)
 {
     ASSERT(element);
     m_element = element;
     m_initialFrame = screenRectOfContents(m_element.get());
     m_page->injectedBundleFullScreenClient().enterFullScreenForElement(m_page.get(), element);
 }
 
 void WebFullScreenManager::exitFullScreenForElement(WebCore::Element* element)
 {
+    ASSERT(element);
+    ASSERT(m_element == element);
     m_page->injectedBundleFullScreenClient().exitFullScreenForElement(m_page.get(), element);
 }
 
 void WebFullScreenManager::willEnterFullScreen()
 {
     ASSERT(m_element);
     m_element->document()->webkitWillEnterFullScreenForElement(m_element.get());
     m_element->document()->updateLayout();
     m_page->forceRepaintWithoutCallback();
     m_finalFrame = screenRectOfContents(m_element.get());
@@ skipping 22 matching lines @@
 
 void WebFullScreenManager::setAnimatingFullScreen(bool animating)
 {
     ASSERT(m_element);
     m_element->document()->setAnimatingFullScreen(animating);
 }
 
 } // namespace WebKit
 
 #endif // ENABLE(FULLSCREEN_API)