Make Element.animate work in dart2js Chrome

tools/dom/scripts/systemhtml.py

 #!/usr/bin/python
 # 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.
 
 """This module provides shared functionality for the system to generate
 Dart:html APIs from the IDL database."""
 
 import emitter
 import logging
@@ skipping 40 matching lines @@
     'ConsoleBase.timeStamp',
     'ConsoleBase.trace',
     'ConsoleBase.warn',
     'WebKitCSSKeyframesRule.insertRule',
     'CSSStyleDeclaration.setProperty',
     'CSSStyleDeclaration.__propertyQuery__',
     'Document.createNodeIterator',
     'Document.createTreeWalker',
     'DOMException.name',
     'DOMException.toString',
+    'Element.animate',
     'Element.createShadowRoot',
     'Element.insertAdjacentElement',
     'Element.insertAdjacentHTML',
     'Element.insertAdjacentText',
     'Element.remove',
     'Element.shadowRoot',
     'Element.matches',
     'ElementEvents.mouseWheel',
     'ElementEvents.transitionEnd',
     'FileReader.result',
@@ skipping 329 matching lines @@
   'SVGFESpecularLightingElement',
   'SVGFESpotLightElement',
   'SVGFETileElement',
   'SVGFETurbulenceElement',
   'SVGFilterElement',
   'SVGForeignObjectElement',
   'SVGSetElement',
 ]
 
 js_support_checks = dict({
+    'AnimationPlayer': "JS('bool', '!!(document.body.animate)')",
     'AudioContext': "JS('bool', '!!(window.AudioContext ||"
         " window.webkitAudioContext)')",
     'Crypto':
         "JS('bool', '!!(window.crypto && window.crypto.getRandomValues)')",
     'Database': "JS('bool', '!!(window.openDatabase)')",
     'DOMPoint': "JS('bool', '!!(window.DOMPoint) || !!(window.WebKitPoint)')",
     'ApplicationCache': "JS('bool', '!!(window.applicationCache)')",
     'DOMFileSystem': "JS('bool', '!!(window.webkitRequestFileSystem)')",
     'FormData': "JS('bool', '!!(window.FormData)')",
     'HashChangeEvent': "Device.isEventTypeSupported('HashChangeEvent')",
@@ skipping 855 matching lines @@
 
   def AddFile(self, basename, library_name, path):
     self._libraries[library_name].AddFile(path)
 
   def AddTypeEntry(self, library_name, idl_name, dart_name):
     self._libraries[library_name].AddTypeEntry(idl_name, dart_name)
 
   def Emit(self, emitter, auxiliary_dir):
     for lib in self._libraries.values():
       lib.Emit(emitter, auxiliary_dir)