LayoutObject::adjustStyleDifference doesn't check backgroundColor when repainting

Source/core/style/ComputedStyle.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 397 matching lines @@
     bool hasMarginBeforeQuirk() const { return marginBefore().quirk(); }
     bool hasMarginAfterQuirk() const { return marginAfter().quirk(); }
 
     bool hasBackgroundImage() const { return m_background->background().hasImage(); }
     bool hasFixedBackgroundImage() const { return m_background->background().hasFixedImage(); }
 
     bool hasEntirelyFixedBackground() const;
 
     bool hasAppearance() const { return appearance() != NoControlPart; }
 
+    bool isBackgroundColorCurrentColor() const { return backgroundColor().isCurrentColor() || visitedLinkBackgroundColor().isCurrentColor(); }
+
     bool hasBackground() const
     {
         Color color = visitedDependentColor(CSSPropertyBackgroundColor);
         if (color.alpha())
             return true;
         return hasBackgroundImage();
     }
 
     LayoutRectOutsets imageOutsets(const NinePieceImage&) const;
     bool hasBorderImageOutsets() const
@@ skipping 1513 matching lines @@
 }
 
 inline bool ComputedStyle::hasPseudoElementStyle() const
 {
     return noninherited_flags.pseudoBits & PSEUDO_ELEMENT_MASK;
 }
 
 } // namespace blink
 
 #endif // ComputedStyle_h