Declare onFinish event handler for AnimationPlayer

Source/core/animation/AnimationPlayer.cpp

Index: Source/core/animation/AnimationPlayer.cpp
diff --git a/Source/core/animation/AnimationPlayer.cpp b/Source/core/animation/AnimationPlayer.cpp
index 48351215c4e60238decff833135fed84c1410bb3..ab5d25aa8c3ef9772fae83935c42fe6c1d1c4914 100644
--- a/Source/core/animation/AnimationPlayer.cpp
+++ b/Source/core/animation/AnimationPlayer.cpp
@@ -238,6 +238,20 @@ void AnimationPlayer::finish(ExceptionState& exceptionState)
     ASSERT(finished());
 }
 
+const AtomicString& AnimationPlayer::interfaceName() const
+{
+    return EventTargetNames::AnimationPlayer;
+}
+
+ExecutionContext* AnimationPlayer::executionContext() const
+{
+    if (m_timeline) {
+        if (Document* document = m_timeline->document())
+            return document->contextDocument().get();
+    }
+    return 0;
+}
+
 void AnimationPlayer::setPlaybackRate(double playbackRate)
 {
     if (!std::isfinite(playbackRate))