Avoid leaking ThreadingPrimitives.h from StackStats.h when collection is off.

Source/core/rendering/RenderTextTrackCue.cpp

 /*
  * Copyright (C) 2012 Victor Carbune (victor@rosedu.org)
  *
  * 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 22 matching lines @@
 namespace WebCore {
 
 RenderTextTrackCue::RenderTextTrackCue(TextTrackCueBox* element)
     : RenderBlock(element)
     , m_cue(element->getCue())
 {
 }
 
 void RenderTextTrackCue::layout()
 {
-    StackStats::LayoutCheckPoint layoutCheckPoint;
     RenderBlock::layout();
 
 #if ENABLE(WEBVTT_REGIONS)
     // If WebVTT Regions are used, the regular WebVTT layout algorithm is no
     // longer necessary, since cues having the region parameter set do not have
     // any positioning parameters. Also, in this case, the regions themselves
     // have positioning information.
     if (!m_cue->regionId().isEmpty())
         return;
 #endif
@@ skipping 230 matching lines @@
     setX(right);
 }
 
 void RenderTextTrackCue::repositionCueSnapToLinesNotSet()
 {
     // FIXME: Implement overlapping detection when snap-to-lines is not set. http://wkb.ug/84296
 }
 
 } // namespace WebCore