Enable WebVTT regions for runtime testing, updated tests and minor fixes

Source/core/html/HTMLMediaElement.cpp

 /*
  * 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 1298 matching lines @@
 
 void HTMLMediaElement::textTrackRemoveCue(TextTrack*, PassRefPtr<TextTrackCue> cue)
 {
     // Negative duration cues need to be treated in the interval tree as
     // zero-length cues.
     double endTime = max(cue->startTime(), cue->endTime());
 
     CueInterval interval = m_cueTree.createInterval(cue->startTime(), endTime, cue.get());
     m_cueTree.remove(interval);
 
+    // Since the cue will be removed from the media element and likely the
+    // TextTrack might also be destructed, notifying the region of the cue
+    // removal shouldn't be done.
+    cue->notifyRegionWhenRemovingDisplayTree(false);
+
     size_t index = m_currentlyActiveCues.find(interval);
     if (index != kNotFound) {
         m_currentlyActiveCues.remove(index);
         cue->setIsActive(false);
     }
-
     cue->removeDisplayTree();
     updateActiveTextTrackCues(currentTime());
+
+    cue->notifyRegionWhenRemovingDisplayTree(true);
 }
 
 
 bool HTMLMediaElement::isSafeToLoadURL(const KURL& url, InvalidURLAction actionIfInvalid)
 {
     if (!url.isValid()) {
         LOG(Media, "HTMLMediaElement::isSafeToLoadURL(%s) -> FALSE because url is invalid", urlForLoggingMedia(url).utf8().data());
         return false;
     }
 
@@ skipping 2582 matching lines @@
 {
     m_restrictions = NoRestrictions;
 }
 
 void HTMLMediaElement::mediaPlayerScheduleLayerUpdate()
 {
     scheduleLayerUpdate();
 }
 
 }