Make LayoutState always be RAII

Source/core/rendering/RenderVTTCue.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 38 matching lines @@
     // have positioning information.
     if (!m_cue->regionId().isEmpty())
         return;
 
     LayoutStateMaintainer statePusher(*this, locationOffset());
 
     if (m_cue->snapToLines())
         repositionCueSnapToLinesSet();
     else
         repositionCueSnapToLinesNotSet();
-
-    statePusher.pop();
 }
 
 bool RenderVTTCue::findFirstLineBox(InlineFlowBox*& firstLineBox)
 {
     if (firstChild()->isRenderInline())
         firstLineBox = toRenderInline(firstChild())->firstLineBox();
     else
         return false;
 
     return true;
@@ skipping 193 matching lines @@
     }
 }
 
 void RenderVTTCue::repositionCueSnapToLinesNotSet()
 {
     // FIXME: Implement overlapping detection when snap-to-lines is not set. http://wkb.ug/84296
 }
 
 } // namespace WebCore