Throw TypeError if easing string is invalid.

third_party/WebKit/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 43 matching lines @@
     {
         EffectModel* effect = EffectInput::convert(&element, effectInput, executionContext, exceptionState);
         if (exceptionState.hadException())
             return 0;
         return animateInternal(element, effect, TimingInput::convert(duration));
     }
 
     static Animation* animate(ExecutionContext* executionContext, Element& element, const EffectModelOrDictionarySequenceOrDictionary& effectInput, const KeyframeEffectOptions& options, ExceptionState& exceptionState)
     {
         EffectModel* effect = EffectInput::convert(&element, effectInput, executionContext, exceptionState);
-        if (exceptionState.hadException())
+        Timing timing;
+        bool success = TimingInput::convert(options, timing, &element.document(), exceptionState);
+        if (!success || exceptionState.hadException())
             return 0;
 
-        Animation* animation = animateInternal(element, effect, TimingInput::convert(options, &element.document()));
+        Animation* animation = animateInternal(element, effect, timing);
         animation->setId(options.id());
         return animation;
     }
 
     static Animation* animate(ExecutionContext* executionContext, Element& element, const EffectModelOrDictionarySequenceOrDictionary& effectInput, ExceptionState& exceptionState)
     {
         EffectModel* effect = EffectInput::convert(&element, effectInput, executionContext, exceptionState);
         if (exceptionState.hadException())
             return 0;
         return animateInternal(element, effect, Timing());
@@ skipping 18 matching lines @@
     static Animation* animateInternal(Element& element, EffectModel* effect, const Timing& timing)
     {
         KeyframeEffect* keyframeEffect = KeyframeEffect::create(&element, effect, timing);
         return element.document().timeline().play(keyframeEffect);
     }
 };
 
 } // namespace blink
 
 #endif // ElementAnimation_h