Add a comment to a subtle use of OwnPtr::release()

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 205 matching lines @@
             (*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));
         HashSet<RefPtr<Player> > players;
         for (HashSet<RefPtr<InertAnimation> >::const_iterator animationsIter = iter->animations.begin(); animationsIter != iter->animations.end(); ++animationsIter) {
             const InertAnimation* inertAnimation = animationsIter->get();
+            // The event delegate is set on the the first animation only. We
+            // rely on the behavior of OwnPtr::release() to achieve this.
             RefPtr<Animation> animation = Animation::create(element, inertAnimation->effect(), inertAnimation->specified(), eventDelegate.release());
             players.add(element->document().timeline()->play(animation.get()));
         }
         m_animations.set(iter->name, players);
     }
 }
 
 void CSSAnimations::cancel()
 {
     for (AnimationMap::iterator iter = m_animations.begin(); iter != m_animations.end(); ++iter) {
@@ skipping 150 matching lines @@
     case CSSPropertyWordSpacing:
     case CSSPropertyZIndex:
     case CSSPropertyZoom:
         return true;
     default:
         return false;
     }
 }
 
 } // namespace WebCore