Remove PosterWaitingForVideo which is redundant

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 300 matching lines @@
     HTMLMediaElement(const QualifiedName&, Document&);
     virtual ~HTMLMediaElement();
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
     virtual void finishParsingChildren() override final;
     virtual bool isURLAttribute(const Attribute&) const override;
     virtual void attach(const AttachContext& = AttachContext()) override;
 
     virtual void didMoveToNewDocument(Document& oldDocument) override;
 
-    enum DisplayMode { Unknown, Poster, PosterWaitingForVideo, Video };
+    enum DisplayMode { Unknown, Poster, Video };
     DisplayMode displayMode() const { return m_displayMode; }
     virtual void setDisplayMode(DisplayMode mode) { m_displayMode = mode; }
 
     void setControllerInternal(PassRefPtrWillBeRawPtr<MediaController>);
 
     bool ignoreTrackDisplayUpdateRequests() const { return m_ignoreTrackDisplayUpdate > 0; }
     void beginIgnoringTrackDisplayUpdateRequests();
     void endIgnoringTrackDisplayUpdateRequests();
 
 private:
@@ skipping 298 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