Use reference for FillLayer if possible

Source/core/animation/css/CSSAnimatableValueFactory.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 166 matching lines @@
 }
 
 inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromBackgroundPosition(const Length& length, bool originIsSet, BackgroundEdgeOrigin origin, const RenderStyle& style)
 {
     if (!originIsSet || origin == LeftEdge || origin == TopEdge)
         return createFromLength(length, style);
     return createFromLength(length.subtractFromOneHundredPercent(), style);
 }
 
 template<CSSPropertyID property>
-inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromFillLayers(const FillLayer* fillLayer, const RenderStyle& style)
+inline static PassRefPtrWillBeRawPtr<AnimatableValue> createFromFillLayers(const FillLayer& fillLayers, const RenderStyle& style)
 {
-    ASSERT(fillLayer);
     WillBeHeapVector<RefPtrWillBeMember<AnimatableValue> > values;
-    while (fillLayer) {
+    for (const FillLayer* fillLayer = &fillLayers; fillLayer; fillLayer = fillLayer->next()) {
         if (property == CSSPropertyBackgroundImage || property == CSSPropertyWebkitMaskImage) {
             if (!fillLayer->isImageSet())
                 break;
             values.append(createFromStyleImage(fillLayer->image()));
         } else if (property == CSSPropertyBackgroundPositionX || property == CSSPropertyWebkitMaskPositionX) {
             if (!fillLayer->isXPositionSet())
                 break;
             values.append(createFromBackgroundPosition(fillLayer->xPosition(), fillLayer->isBackgroundXOriginSet(), fillLayer->backgroundXOrigin(), style));
         } else if (property == CSSPropertyBackgroundPositionY || property == CSSPropertyWebkitMaskPositionY) {
             if (!fillLayer->isYPositionSet())
                 break;
             values.append(createFromBackgroundPosition(fillLayer->yPosition(), fillLayer->isBackgroundYOriginSet(), fillLayer->backgroundYOrigin(), style));
         } else if (property == CSSPropertyBackgroundSize || property == CSSPropertyWebkitMaskSize) {
             if (!fillLayer->isSizeSet())
                 break;
             values.append(createFromFillSize(fillLayer->size(), style));
         } else {
             ASSERT_NOT_REACHED();
         }
-        fillLayer = fillLayer->next();
     }
     return AnimatableRepeatable::create(values);
 }
 
 PassRefPtrWillBeRawPtr<AnimatableValue> CSSAnimatableValueFactory::createFromColor(CSSPropertyID property, const RenderStyle& style)
 {
     Color color = style.colorIncludingFallback(property, false);
     Color visitedLinkColor = style.colorIncludingFallback(property, true);
     return AnimatableColor::create(color, visitedLinkColor);
 }
@@ skipping 291 matching lines @@
     case CSSPropertyZoom:
         return createFromDouble(style.zoom());
     default:
         ASSERT_NOT_REACHED();
         // This return value is to avoid a release crash if possible.
         return AnimatableUnknown::create(nullptr);
     }
 }
 
 } // namespace WebCore