Replace HTMLMediaElement::isVideo() with isHTMLVideoElement

Source/core/html/HTMLVideoElement.h

 /*
  * Copyright (C) 2007, 2008, 2009, 2010 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 60 matching lines @@
 
 private:
     HTMLVideoElement(Document&);
 
     virtual bool rendererIsNeeded(const RenderStyle&) OVERRIDE;
     virtual RenderObject* createRenderer(RenderStyle*) OVERRIDE;
     virtual void attach(const AttachContext& = AttachContext()) OVERRIDE;
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) OVERRIDE;
     virtual bool isPresentationAttribute(const QualifiedName&) const OVERRIDE;
     virtual void collectStyleForPresentationAttribute(const QualifiedName&, const AtomicString&, MutableStylePropertySet*) OVERRIDE;
-    virtual bool isVideo() const OVERRIDE { return true; }
     virtual bool hasVideo() const OVERRIDE { return player() && player()->hasVideo(); }
     virtual bool isURLAttribute(const Attribute&) const OVERRIDE;
     virtual const AtomicString imageSourceURL() const OVERRIDE;
 
     bool hasAvailableVideoFrame() const;
     virtual void updateDisplayState() OVERRIDE;
     virtual void didMoveToNewDocument(Document& oldDocument) OVERRIDE;
     virtual void setDisplayMode(DisplayMode) OVERRIDE;
 
     OwnPtr<HTMLImageLoader> m_imageLoader;
 
     AtomicString m_defaultPosterURL;
 };
 
 } //namespace
 
 #endif