Remove background obscuration checks.

sky/engine/core/rendering/style/RenderStyle.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 1351 matching lines @@
     StyleColor textFillColor() const { return rareInheritedData->textFillColor(); }
     StyleColor textStrokeColor() const { return rareInheritedData->textStrokeColor(); }
 
     StyleColor textDecorationColor() const { return rareNonInheritedData->m_textDecorationColor; }
 
     void addAppliedTextDecoration(const AppliedTextDecoration&);
 
     // FIXME(sky): Combine these first two.
     bool diffNeedsFullLayoutAndPaintInvalidation(const RenderStyle& other) const;
     bool diffNeedsFullLayout(const RenderStyle& other) const;
-    bool diffNeedsPaintInvalidation(const RenderStyle& other) const;
     bool diffNeedsRecompositeLayer(const RenderStyle& other) const;
     void updatePropertySpecificDifferences(const RenderStyle& other, StyleDifference&) const;
 };
 
 inline bool RenderStyle::isSharable() const
 {
     return !unique();
 }
 
 inline bool RenderStyle::setTextOrientation(TextOrientation textOrientation)
 {
     if (compareEqual(rareInheritedData->m_textOrientation, textOrientation))
         return false;
 
     rareInheritedData.access()->m_textOrientation = textOrientation;
     return true;
 }
 
 float calcBorderRadiiConstraintScaleFor(const FloatRect&, const FloatRoundedRect::Radii&);
 
 } // namespace blink
 
 #endif  // SKY_ENGINE_CORE_RENDERING_STYLE_RENDERSTYLE_H_