Make Element.animate work in dart2js Chrome

tests/html/html.status

Index: tests/html/html.status
diff --git a/tests/html/html.status b/tests/html/html.status
index ae1919429b3414b8f44f60cee7eb9f330fcf28b5..867ff0d94efaf22e45279a88323599a3080482ba 100644
--- a/tests/html/html.status
+++ b/tests/html/html.status
@@ -15,6 +15,7 @@ indexeddb_4_test: Skip # Issue 19726
 mouse_event_test: Fail # Issue 20437
 worker_api_test: Fail # Issue 10223
 media_stream_test/constructors: Pass, Crash # Issue 22267
+element_animate_test: Fail # Not supported on Dartium
 
 [ $compiler == none && $mode == debug && ($runtime == drt || $runtime == dartium || $runtime == ContentShellOnAndroid) ]
 datalistelement_test: Skip # Issue 20540
@@ -33,6 +34,7 @@ storage_quota_test: Fail # Support for promises.
 
 [ $compiler == dart2js && ($runtime == safari || $runtime == safarimobilesim || $runtime == ff  || $ie) ]
 custom/entered_left_view_test/viewless_document: Fail # Polyfill does not handle this
+element_animate_test: Fail # Element.animate not supported on these browsers.
 
 [ $compiler == none && $runtime == dartium && $system == macos]
 canvasrenderingcontext2d_test/drawImage_video_element_dataUrl: Pass,Fail # Issue 11834