Animations: Fix bug where getAnimationPlayers() crashes

Source/core/animation/ElementAnimation.h

 /*
  * 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 73 matching lines @@
     {
         RefPtrWillBeRawPtr<AnimationEffect> effect = EffectInput::convert(&element, keyframeDictionaryVector, exceptionState);
         if (exceptionState.hadException())
             return 0;
         ASSERT(effect);
         return animateInternal(element, effect.release(), Timing());
     }
 
     static WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> > getAnimationPlayers(Element& element)
     {
-        WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> > animationPlayers = WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> >();
+        WillBeHeapVector<RefPtrWillBeMember<AnimationPlayer> > animationPlayers;
+
+        if (!element.hasActiveAnimations())
+            return animationPlayers;
+
         const AnimationPlayerCountedSet& players = element.activeAnimations()->players();
 
         for (AnimationPlayerCountedSet::const_iterator it = players.begin(); it != players.end(); ++it) {
             ASSERT(it->key->source());
             if (it->key->source()->isCurrent())
                 animationPlayers.append(it->key);
         }
         return animationPlayers;
     }
 
 private:
     static AnimationPlayer* animateInternal(Element& element, PassRefPtrWillBeRawPtr<AnimationEffect> effect, const Timing& timing)
     {
         if (RuntimeEnabledFeatures::webAnimationsElementAnimateEnabled()) {
             RefPtrWillBeRawPtr<Animation> animation = Animation::create(&element, effect, timing);
             return element.document().timeline().play(animation.get());
         }
         return 0;
     }
 };
 
 } // namespace blink
 
 #endif // ElementAnimation_h