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

Source/core/dom/Fullscreen.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
@@ skipping 59 matching lines @@
 {
     // A fullscreen element ready check for an element |element| returns true if all of the
     // following are true, and false otherwise:
 
     // |element| is in a document.
     if (!element.inDocument())
         return false;
 
     // |element|'s node document's fullscreen enabled flag is set.
     if (!fullscreenIsAllowedForAllOwners(element.document())) {
-        if (requestType == Fullscreen::InternalVideoRequest)
+        if (requestType == Fullscreen::PrefixedVideoRequest)
             UseCounter::count(element.document(), UseCounter::VideoFullscreenAllowedExemption);
         else
             return false;
     }
 
     // |element|'s node document's fullscreen element stack is either empty or its top element is an
     // inclusive ancestor of |element|.
     if (const Element* topElement = Fullscreen::fullscreenElementFrom(element.document())) {
         if (!topElement->contains(&element))
             return false;
@@ skipping 525 matching lines @@
 #if ENABLE(OILPAN)
     visitor->trace(m_fullScreenElement);
     visitor->trace(m_fullScreenElementStack);
     visitor->trace(m_eventQueue);
 #endif
     WillBeHeapSupplement<Document>::trace(visitor);
     DocumentLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink