Remove stale files from lib/html/src.

lib/html/src/AnimationEventWrappingImplementation.dart

Index: lib/html/src/AnimationEventWrappingImplementation.dart
diff --git a/lib/html/src/AnimationEventWrappingImplementation.dart b/lib/html/src/AnimationEventWrappingImplementation.dart
deleted file mode 100644
index 711265bfc0fc0a2a8eb1a2c41a684b1814888bd7..0000000000000000000000000000000000000000
--- a/lib/html/src/AnimationEventWrappingImplementation.dart
+++ /dev/null
@@ -1,33 +0,0 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-class AnimationEventWrappingImplementation extends EventWrappingImplementation implements AnimationEvent {
-  static String _name;
-
-  AnimationEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
-
-  static String get _eventName() {
-    if (_name != null) return _name;
-
-    try {
-      dom.document.createEvent("WebKitAnimationEvent");
-      _name = "WebKitAnimationEvent";
-    } catch (e) {
-      _name = "AnimationEvent";
-    }
-    return _name;
-  }
-
-  factory AnimationEventWrappingImplementation(String type, String propertyName,
-      double elapsedTime, [bool canBubble = true, bool cancelable = true]) {
-    final e = dom.document.createEvent(_eventName);
-    e.initWebKitAnimationEvent(
-        type, canBubble, cancelable, propertyName, elapsedTime);
-    return LevelDom.wrapAnimationEvent(e);
-  }
-
-  String get animationName() => _ptr.animationName;
-
-  num get elapsedTime() => _ptr.elapsedTime;
-}