Sync the AnimationEvent and TransitionEvent interfaces with the specs

Source/core/events/AnimationEvent.cpp

 /*
  * Copyright (C) 2007, 2008 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 
 namespace blink {
 
 AnimationEvent::AnimationEvent()
     : m_elapsedTime(0.0)
 {
 }
 
 AnimationEvent::AnimationEvent(const AtomicString& type, const AnimationEventInit& initializer)
     : Event(type, initializer)
-    , m_elapsedTime(0.0)
+    , m_animationName(initializer.animationName())
+    , m_elapsedTime(initializer.elapsedTime())
 {
-    if (initializer.hasAnimationName())
-        m_animationName = initializer.animationName();
-    if (initializer.hasElapsedTime())
-        m_elapsedTime = initializer.elapsedTime();
 }
 
 AnimationEvent::AnimationEvent(const AtomicString& type, const String& animationName, double elapsedTime)
     : Event(type, true, true)
     , m_animationName(animationName)
     , m_elapsedTime(elapsedTime)
 {
 }
 
 AnimationEvent::~AnimationEvent()
@@ skipping 14 matching lines @@
 {
     return EventNames::AnimationEvent;
 }
 
 DEFINE_TRACE(AnimationEvent)
 {
     Event::trace(visitor);
 }
 
 } // namespace blink