Add infrastructure for partial layouts

Source/core/rendering/RenderTextTrackCue.h

 /*
  * 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 23 matching lines @@
 namespace WebCore {
 
 class TextTrackCueBox;
 
 class RenderTextTrackCue FINAL : public RenderBlock {
 public:
     explicit RenderTextTrackCue(TextTrackCueBox*);
 
 private:
     virtual void layout() OVERRIDE;
+    virtual bool supportsPartialLayout() const OVERRIDE { return false; }
 
     bool isOutside() const;
     bool isOverlapping() const;
     bool shouldSwitchDirection(InlineFlowBox*, LayoutUnit) const;
 
     void moveBoxesByStep(LayoutUnit);
     bool switchDirection(bool&, LayoutUnit&);
 
     bool findFirstLineBox(InlineFlowBox*&);
     bool initializeLayoutParameters(InlineFlowBox*, LayoutUnit&, LayoutUnit&);
     void placeBoxInDefaultPosition(LayoutUnit, bool&);
     void repositionCueSnapToLinesSet();
     void repositionCueSnapToLinesNotSet();
     void repositionGenericCue();
 
     TextTrackCue* m_cue;
     FloatPoint m_fallbackPosition;
 };
 
 } // namespace WebCore
 
 #endif // RenderTextTrackCue_h