Mark when we may have been invalidated to early out on repaintTreeAfterLayout.

Source/core/rendering/RenderBox.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2006, 2007 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 496 matching lines @@
     virtual void paintObject(PaintInfo&, const LayoutPoint&) { ASSERT_NOT_REACHED(); }
     virtual void paintBoxDecorations(PaintInfo&, const LayoutPoint&);
     virtual void paintMask(PaintInfo&, const LayoutPoint&);
     virtual void paintClippingMask(PaintInfo&, const LayoutPoint&);
     virtual void imageChanged(WrappedImagePtr, const IntRect* = 0) OVERRIDE;
 
     // Called when a positioned object moves but doesn't necessarily change size.  A simplified layout is attempted
     // that just updates the object's position. If the size does change, the object remains dirty.
     bool tryLayoutDoingPositionedMovementOnly()
     {
+        setMayNeedInvalidation(true);
+
         LayoutUnit oldWidth = width();
         updateLogicalWidth();
         // If we shrink to fit our width may have changed, so we still need full layout.
         if (oldWidth != width())
             return false;
         updateLogicalHeight();
         return true;
     }
 
     virtual PositionWithAffinity positionForPoint(const LayoutPoint&) OVERRIDE;
@@ skipping 247 matching lines @@
         if (UNLIKELY(inlineBoxWrapper() != 0))
             deleteLineBoxWrapper();
     }
 
     ensureRareData().m_inlineBoxWrapper = boxWrapper;
 }
 
 } // namespace WebCore
 
 #endif // RenderBox_h