Throw TypeError if easing string is invalid.

third_party/WebKit/Source/core/animation/TimingInput.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef TimingInput_h
 #define TimingInput_h
 
 #include "core/CoreExport.h"
 #include "core/animation/Timing.h"
 #include "wtf/Allocator.h"
 
 namespace blink {
 
 class Dictionary;
 class Document;
+class ExceptionState;
 class KeyframeEffectOptions;
 
 class CORE_EXPORT TimingInput {
     STATIC_ONLY(TimingInput);
 public:
-    static Timing convert(const KeyframeEffectOptions& timingInput, Document*);
+    static bool convert(const KeyframeEffectOptions& timingInput, Timing& timingOutput, Document*, ExceptionState&);
     static Timing convert(double duration);
 
     static void setStartDelay(Timing&, double startDelay);
     static void setEndDelay(Timing&, double endDelay);
     static void setFillMode(Timing&, const String& fillMode);
     static void setIterationStart(Timing&, double iterationStart);
     static void setIterationCount(Timing&, double iterationCount);
     static void setIterationDuration(Timing&, double iterationDuration);
     static void setPlaybackRate(Timing&, double playbackRate);
     static void setPlaybackDirection(Timing&, const String& direction);
-    static void setTimingFunction(Timing&, const String& timingFunctionString, Document*);
+    static bool setTimingFunction(Timing&, const String& timingFunctionString, Document*, ExceptionState&);
 };
 
 } // namespace blink
 
 #endif