Use reference for FillLayer if possible

Source/core/css/resolver/StyleResourceLoader.cpp

Index: Source/core/css/resolver/StyleResourceLoader.cpp
diff --git a/Source/core/css/resolver/StyleResourceLoader.cpp b/Source/core/css/resolver/StyleResourceLoader.cpp
index 9025bf04f78a5cf7ec823f02ef7b4ddd2d9f0cee..1074bbbcdaeb7bb540355d5d5d6a428774aade2c 100644
--- a/Source/core/css/resolver/StyleResourceLoader.cpp
+++ b/Source/core/css/resolver/StyleResourceLoader.cpp
@@ -125,7 +125,7 @@ void StyleResourceLoader::loadPendingImages(RenderStyle* style, ElementStyleReso
 
         switch (currentProperty) {
         case CSSPropertyBackgroundImage: {
-            for (FillLayer* backgroundLayer = style->accessBackgroundLayers(); backgroundLayer; backgroundLayer = backgroundLayer->next()) {
+            for (FillLayer* backgroundLayer = &style->accessBackgroundLayers(); backgroundLayer; backgroundLayer = backgroundLayer->next()) {
                 if (backgroundLayer->image() && backgroundLayer->image()->isPendingImage())
                     backgroundLayer->setImage(loadPendingImage(toStylePendingImage(backgroundLayer->image()), elementStyleResources.deviceScaleFactor()));
             }
@@ -182,7 +182,7 @@ void StyleResourceLoader::loadPendingImages(RenderStyle* style, ElementStyleReso
             break;
         }
         case CSSPropertyWebkitMaskImage: {
-            for (FillLayer* maskLayer = style->accessMaskLayers(); maskLayer; maskLayer = maskLayer->next()) {
+            for (FillLayer* maskLayer = &style->accessMaskLayers(); maskLayer; maskLayer = maskLayer->next()) {
                 if (maskLayer->image() && maskLayer->image()->isPendingImage())
                     maskLayer->setImage(loadPendingImage(toStylePendingImage(maskLayer->image()), elementStyleResources.deviceScaleFactor()));
             }