Have Node::document() return a reference instead of a pointer

Source/core/animation/css/CSSAnimations.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 204 matching lines @@
     OwnPtr<CSSAnimationUpdate> update = m_pendingUpdate.release();
 
     for (Vector<AtomicString>::const_iterator iter = update->cancelledAnimationNames().begin(); iter != update->cancelledAnimationNames().end(); ++iter)
         m_animations.take(*iter)->cancel();
 
     // FIXME: Apply updates to play-state.
 
     for (Vector<CSSAnimationUpdate::NewAnimation>::const_iterator iter = update->newAnimations().begin(); iter != update->newAnimations().end(); ++iter) {
         OwnPtr<CSSAnimations::EventDelegate> eventDelegate = adoptPtr(new EventDelegate(element, iter->name));
         RefPtr<Animation> animation = Animation::create(element, iter->animation->effect(), iter->animation->specified(), eventDelegate.release());
-        RefPtr<Player> player = element->document()->timeline()->play(animation.get());
+        RefPtr<Player> player = element->document().timeline()->play(animation.get());
         m_animations.set(iter->name, player.get());
     }
 }
 
 void CSSAnimations::cancel()
 {
     for (AnimationMap::iterator iter = m_animations.begin(); iter != m_animations.end(); ++iter)
         iter->value->cancel();
 
     m_animations.clear();
     m_pendingUpdate = nullptr;
 }
 
 void CSSAnimations::EventDelegate::maybeDispatch(Document::ListenerType listenerType, AtomicString& eventName, double elapsedTime)
 {
-    if (m_target->document()->hasListenerType(listenerType))
-        m_target->document()->timeline()->addEventToDispatch(m_target, WebKitAnimationEvent::create(eventName, m_name, elapsedTime));
+    if (m_target->document().hasListenerType(listenerType))
+        m_target->document().timeline()->addEventToDispatch(m_target, WebKitAnimationEvent::create(eventName, m_name, elapsedTime));
 }
 
 void CSSAnimations::EventDelegate::onEventCondition(const TimedItem* timedItem, bool isFirstSample, TimedItem::Phase previousPhase, double previousIteration)
 {
     // Events for a single document are queued and dispatched as a group at
     // the end of DocumentTimeline::serviceAnimations.
     // FIXME: Events which are queued outside of serviceAnimations should
     // trigger a timer to dispatch when control is released.
     const TimedItem::Phase currentPhase = timedItem->phase();
     const double currentIteration = timedItem->currentIteration();
@@ skipping 126 matching lines @@
     case CSSPropertyWordSpacing:
     case CSSPropertyZIndex:
     case CSSPropertyZoom:
         return true;
     default:
         return false;
     }
 }
 
 } // namespace WebCore