Have Document::timeline() / Document::transitionTimeline() return a reference

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 30 matching lines @@
 #include "core/frame/LocalFrame.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/compositing/RenderLayerCompositor.h"
 
 namespace WebCore {
 
 namespace {
 
 void updateAnimationTiming(Document& document)
 {
-    document.timeline()->serviceAnimations();
-    document.transitionTimeline()->serviceAnimations();
+    document.timeline().serviceAnimations();
+    document.transitionTimeline().serviceAnimations();
 }
 
 } // namespace
 
 void DocumentAnimations::dispatchAnimationEvents(Document& document)
 {
-    document.timeline()->dispatchEvents();
-    document.transitionTimeline()->dispatchEvents();
+    document.timeline().dispatchEvents();
+    document.transitionTimeline().dispatchEvents();
 }
 
 void DocumentAnimations::dispatchAnimationEventsAsync(Document& document)
 {
-    document.timeline()->dispatchEventsAsync();
-    document.transitionTimeline()->dispatchEventsAsync();
+    document.timeline().dispatchEventsAsync();
+    document.transitionTimeline().dispatchEventsAsync();
 }
 
 void DocumentAnimations::updateAnimationTimingForAnimationFrame(Document& document, double monotonicAnimationStartTime)
 {
     document.animationClock().updateTime(monotonicAnimationStartTime);
     updateAnimationTiming(document);
 }
 
 void DocumentAnimations::updateAnimationTimingForGetComputedStyle(Node& node, CSSPropertyID property)
 {
     if (!node.isElementNode())
         return;
     const Element& element = toElement(node);
-    if (element.document().timeline()->hasOutdatedPlayer()) {
+    if (element.document().timeline().hasOutdatedPlayer()) {
         updateAnimationTiming(element.document());
         return;
     }
     if (const ActiveAnimations* activeAnimations = element.activeAnimations()) {
         if (activeAnimations->hasActiveAnimationsOnCompositor(property))
             updateAnimationTiming(element.document());
     }
 }
 
 void DocumentAnimations::startPendingAnimations(Document& document)
 {
     ASSERT(document.lifecycle().state() == DocumentLifecycle::CompositingClean);
     if (document.cssPendingAnimations().startPendingAnimations()) {
         ASSERT(document.view());
         document.view()->scheduleAnimation();
     }
 
     document.animationClock().unfreeze();
 }
 
 } // namespace WebCore