Revert of Remove the allowfullscreen exemption for the video-specific fullscreen API

Source/core/html/HTMLMediaElement.h

 /*
  * 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 203 matching lines @@
     // EventTarget function.
     // Both Node (via HTMLElement) and ActiveDOMObject define this method, which
     // causes an ambiguity error at compile time. This class's constructor
     // ensures that both implementations return document, so return the result
     // of one of them here.
     using HTMLElement::executionContext;
 
     bool hasSingleSecurityOrigin() const { return !m_player || (webMediaPlayer() && webMediaPlayer()->hasSingleSecurityOrigin()); }
 
     bool isFullscreen() const;
+    void enterFullscreen();
+    void exitFullscreen();
 
     bool hasClosedCaptions() const;
     bool closedCaptionsVisible() const;
     void setClosedCaptionsVisible(bool);
 
     void remoteRouteAvailabilityChanged(bool);
     void connectedToRemoteDevice();
     void disconnectedFromRemoteDevice();
 
     // Returns the MediaControls, or null if they have not been added yet.
@@ skipping 349 matching lines @@
 inline bool isHTMLMediaElement(const HTMLElement& element)
 {
     return isHTMLAudioElement(element) || isHTMLVideoElement(element);
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLMediaElement);
 
 } // namespace blink
 
 #endif // HTMLMediaElement_h