Fix scheduleEvent() crash.

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 559 matching lines @@
     bool m_processingPreferenceChange : 1;
     double m_lastTextTrackUpdateTime;
 
     RefPtr<TextTrackList> m_textTracks;
     Vector<RefPtr<TextTrack> > m_textTracksWhenResourceSelectionBegan;
 
     CueIntervalTree m_cueTree;
 
     CueList m_currentlyActiveCues;
     int m_ignoreTrackDisplayUpdate;
+    bool m_inDestructor;
 
 #if ENABLE(WEB_AUDIO)
     // This is a weak reference, since m_audioSourceNode holds a reference to us.
     // The value is set just after the MediaElementAudioSourceNode is created.
     // The value is cleared in MediaElementAudioSourceNode::~MediaElementAudioSourceNode().
     MediaElementAudioSourceNode* m_audioSourceNode;
 #endif
 
     String m_mediaGroup;
     friend class MediaController;
@@ skipping 32 matching lines @@
 
 inline HTMLMediaElement* toMediaElement(Node* node)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!node || isMediaElement(node));
     return static_cast<HTMLMediaElement*>(node);
 }
 
 } //namespace
 
 #endif