Tweak TextTrackCue/VTTCue virtual functions

Source/core/html/track/vtt/VTTCue.cpp

 /*
  * Copyright (c) 2013, Opera Software ASA. 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 205 matching lines @@
     , m_notifyRegion(true)
 {
     ScriptWrappable::init(this);
 }
 
 VTTCue::~VTTCue()
 {
     displayTreeInternal()->remove(ASSERT_NO_EXCEPTION);
 }
 
+#ifndef NDEBUG
 String VTTCue::toString() const
 {
     return String::format("%p id=%s interval=%f-->%f cue=%s)", this, id().utf8().data(), startTime(), endTime(), text().utf8().data());
 }
+#endif
 
 PassRefPtr<VTTCueBox> VTTCue::displayTreeInternal()
 {
     if (!m_displayTree)
         m_displayTree = VTTCueBox::create(document(), this);
     return m_displayTree;
 }
 
 void VTTCue::cueDidChange()
 {
@@ skipping 858 matching lines @@
     return m_cueBackgroundBox->executionContext();
 }
 
 Document& VTTCue::document() const
 {
     ASSERT(m_cueBackgroundBox);
     return m_cueBackgroundBox->document();
 }
 
 } // namespace WebCore