Make RenderObject::style() return a const object

Source/core/animation/DocumentAnimations.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 52 matching lines @@
 {
     if (needsOutdatedAnimationPlayerUpdate(document) || document.timeline().needsAnimationTimingUpdate())
         updateAnimationTiming(document, TimingUpdateOnDemand);
 }
 
 void DocumentAnimations::updateAnimationTimingForGetComputedStyle(Node& node, CSSPropertyID property)
 {
     if (!node.isElementNode())
         return;
     const Element& element = toElement(node);
-    if (LayoutStyle* style = element.layoutStyle()) {
+    if (const LayoutStyle* style = element.layoutStyle()) {
         if ((property == CSSPropertyOpacity && style->isRunningOpacityAnimationOnCompositor())
             || ((property == CSSPropertyTransform || property == CSSPropertyWebkitTransform) && style->isRunningTransformAnimationOnCompositor())
             || (property == CSSPropertyWebkitFilter && style->isRunningFilterAnimationOnCompositor())) {
             updateAnimationTiming(element.document(), TimingUpdateOnDemand);
         }
     }
 }
 
 bool DocumentAnimations::needsOutdatedAnimationPlayerUpdate(const Document& document)
 {
     return document.timeline().hasOutdatedAnimationPlayer();
 }
 
 // FIXME: Rename to updateCompositorAnimations
 void DocumentAnimations::startPendingAnimations(Document& document)
 {
     ASSERT(document.lifecycle().state() == DocumentLifecycle::CompositingClean);
     if (document.compositorPendingAnimations().update()) {
         ASSERT(document.view());
         document.view()->scheduleAnimation();
     }
 
     document.timeline().scheduleNextService();
 }
 
 } // namespace blink