Reduce invalidation on children-needs-layout containers

Source/core/rendering/LayoutRepainter.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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
@@ skipping 37 matching lines @@
         }
         m_oldOutlineBox = m_object.outlineBoundsForRepaint(m_repaintContainer);
     }
 }
 
 bool LayoutRepainter::repaintAfterLayout()
 {
     if (RuntimeEnabledFeatures::repaintAfterLayoutEnabled())
         return false;
 
+    if (!m_object.needsLayoutBecauseOfChildren() && m_object.hasNothingToPaint())

[leviw_travelin_and_unemployed, 2014/03/19 17:47:32]

Why bother with the hasNothingToPaint bitfield instead of just querying the
style here?

[Julien - ping for review, 2014/03/20 01:30:33]

Very good point, sir! Changed.

+        return false;
+
     // Hits in compositing/video/video-controls-layer-creation.html
     DisableCompositingQueryAsserts disabler;
 
     return m_checkForRepaint ? m_object.repaintAfterLayoutIfNeeded(m_repaintContainer, m_object.selfNeedsLayout(), m_oldBounds, m_oldOutlineBox) : false;
 }
 
 } // namespace WebCore