Disallow fullscreen from within <frame>, even with allowfullscreen

Source/core/dom/FullscreenElementStack.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 32 matching lines @@
 namespace WebCore {
 
 using namespace HTMLNames;
 
 static bool fullscreenIsAllowedForAllOwners(const Document& document)
 {
     const HTMLFrameOwnerElement* owner = document.ownerElement();
     if (!owner)
         return true;
     do {
+        if (!isHTMLIFrameElement(owner))
+            return false;
         if (!owner->hasAttribute(allowfullscreenAttr)) {
             if (owner->hasAttribute(webkitallowfullscreenAttr))
                 UseCounter::count(document, UseCounter::PrefixedAllowFullscreenAttribute);
             else
                 return false;
         }
     } while ((owner = owner->document().ownerElement()));
     return true;
 }
 
@@ skipping 518 matching lines @@
 void FullscreenElementStack::trace(Visitor* visitor)
 {
     visitor->trace(m_fullScreenElement);
     visitor->trace(m_fullScreenElementStack);
     visitor->trace(m_fullScreenChangeEventTargetQueue);
     visitor->trace(m_fullScreenErrorEventTargetQueue);
     DocumentSupplement::trace(visitor);
 }
 
 } // namespace WebCore