Use reference for FillLayer if possible

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 174 matching lines @@
 
 static void appendImageIfNotNull(Vector<ImageResource*>& imageResources, const StyleImage* styleImage)
 {
     if (styleImage && styleImage->cachedImage()) {
         ImageResource* imageResource = styleImage->cachedImage();
         if (imageResource && !imageResource->isLoaded())
             imageResources.append(styleImage->cachedImage());
     }
 }
 
-static void appendLayers(Vector<ImageResource*>& images, const FillLayer* styleLayer)
+static void appendLayers(Vector<ImageResource*>& images, const FillLayer& styleLayer)
 {
-    for (const FillLayer* layer = styleLayer; layer; layer = layer->next()) {
+    for (const FillLayer* layer = &styleLayer; layer; layer = layer->next())
         appendImageIfNotNull(images, layer->image());
-    }
 }
 
 static void appendImagesFromStyle(Vector<ImageResource*>& images, RenderStyle& blockStyle)
 {
     appendLayers(images, blockStyle.backgroundLayers());
     appendLayers(images, blockStyle.maskLayers());
 
     const ContentData* contentData = blockStyle.contentData();
     if (contentData && contentData->isImage()) {
         const ImageContentData* imageContentData = static_cast<const ImageContentData*>(contentData);
@@ skipping 4846 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace WebCore