Revert "Add cancelAnimationFrame"

lib/dom/templates/html/frog/impl_Window.darttemplate

 // Copyright (c) 2012, 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 $CLASSNAME$EXTENDS$IMPLEMENTS native "@*DOMWindow" {
 
   _DocumentImpl get document() native "return this.document;";
 
   Window get _top() native "return this.top;";
 
   // Override top to return secure wrapper.
   Window get top() => _DOMWindowCrossFrameImpl._createSafe(_top);
 
   void requestLayoutFrame(TimeoutHandler callback) {
     _addMeasurementFrameCallback(callback);
   }
 
   /** @domName DOMWindow.requestAnimationFrame */
-  int requestAnimationFrame(RequestAnimationFrameCallback callback) {
-    _ensureRequestAnimationFrame();
-    return _requestAnimationFrame(callback);
-  }
+  int requestAnimationFrame(RequestAnimationFrameCallback callback) native '''
+    if (!window.requestAnimationFrame) {
+      window.requestAnimationFrame =
+          window.webkitRequestAnimationFrame ||
+          window.mozRequestAnimationFrame ||
+          window.msRequestAnimationFrame ||
+          window.oRequestAnimationFrame ||
+          function (callback) {
+            window.setTimeout(callback, 16 /* 16ms ~= 60fps */);
+          };
+    }
+    return window.requestAnimationFrame(callback);
+''';
 
-  void cancelAnimationFrame(id) {
-    _ensureRequestAnimationFrame();
-    _cancelAnimationFrame(id);
-  }
-
-  int _requestAnimationFrame(RequestAnimationFrameCallback callback)
-      native 'requestAnimationFrame';
-
-  void _cancelAnimationFrame(int id)
-      native 'cancelAnimationFrame';
-
-  _ensureRequestAnimationFrame() native '''
-   if (this.requestAnimationFrame && this.cancelAnimationFrame) return;
-   vendors = ['ms', 'moz', 'webkit', 'o', ''];
-   for (var i = 0; i < vendors.length && !this.requestAnimationFrame; ++i) {
-     this.requestAnimationFrame = this[vendors[i] + 'RequestAnimationFrame'];
-     this.cancelAnimationFrame =
-         this[vendors[i]+'CancelAnimationFrame'] ||
-         this[vendors[i]+'CancelRequestAnimationFrame'];
-   }
-   if (this.requestAnimationFrame && this.cancelAnimationFrame) return;
-   this.requestAnimationFrame = function(callback) {
-       window.setTimeout(callback, 16 /* 16ms ~= 60fps */);
-   };
-   this.cancelAnimationFrame = function(id) { clearTimeout(id); }
-''';
+  // Protect member 'requestAnimationFrame'.
+  _requestAnimationFrame() native 'requestAnimationFrame';
 
 $!MEMBERS
 }