Use reference for FillLayer if possible

Source/core/rendering/style/CachedUAStyle.h

  /*
  * Copyright (C) 2013 Google, Inc.
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 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 27 matching lines @@
     }
 
     bool hasAppearance;
     BorderData border;
     FillLayer backgroundLayers;
     StyleColor backgroundColor;
 
 private:
     explicit CachedUAStyle(const RenderStyle* style)
         : hasAppearance(true)
-        , backgroundLayers(BackgroundFillLayer)
-        , backgroundColor(StyleColor::currentColor())
+        , border(style->border())
+        , backgroundLayers(style->backgroundLayers())
+        , backgroundColor(style->backgroundColor())
     {
         ASSERT(style->hasAppearance());
-        border = style->border();
-        backgroundLayers = *style->backgroundLayers();
-        backgroundColor = style->backgroundColor();
     }
 };
 
 
 
 } // namespace WebCore
 
 #endif // CachedUAStyle_h