Fix for Animation and other polyfills

pkg/dev_compiler/test/browser/language_tests.js

 // Copyright (c) 2015, 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.
 
 define(['dart_sdk', 'async_helper', 'expect', 'unittest', 'is', 'require'],
       function(dart_sdk, async_helper, expect, unittest, is, require) {
   'use strict';
 
   async_helper = async_helper.async_helper;
   let minitest = expect.minitest;
@@ skipping 27 matching lines @@
 
   // Tests marked with this are still using the deprecated unittest package
   // because they rely on its support for futures and asynchronous tests, which
   // expect and minitest do not handle.
   // TODO(rnystrom): Move all of these away from using the async test API so
   // they can stop using unittest.
   const async_unittest = ['unittest', 'skip', 'fail'];
 
   // The number of expected unittest errors should be zero but unfortunately
   // there are a lot of broken html unittests.
-  let num_expected_unittest_fails = 3;
+  let num_expected_unittest_fails = 4;

[vsm, 2017/01/21 00:52:42]

This is due to: https://github.com/dart-lang/sdk/issues/26730
The other tests pass.

   let num_expected_unittest_errors = 0;
 
   // TODO(jmesserly): separate StrongModeError from other errors.
   let all_status = {
     'language': {
       'assertion_test': fail,
       'async_await_test_none_multi': 'unittest',
       'async_await_test_02_multi': 'unittest',
 
       // Flaky on travis (https://github.com/dart-lang/sdk/issues/27224)
@@ skipping 324 matching lines @@
       'css_rule_list_test': 'fail',
 
       'custom_element_method_clash_test': async_unittest,
       'custom_element_name_clash_test': async_unittest,
       'custom_elements_23127_test': async_unittest,
       'custom_elements_test': async_unittest,
 
       // was https://github.com/dart-lang/sdk/issues/27578, needs triage
       'dom_constructors_test': 'fail',
 
-      'element_animate_test': async_unittest,
+      'element_animate_test': 'unittest',
 
       // https://github.com/dart-lang/sdk/issues/27579.
       'element_classes_test': 'fail',
       'element_classes_svg_test': 'fail',
 
       // Failure: 'Expected 56 to be in the inclusive range [111, 160].'.
       'element_offset_test': 'fail',
 
       'element_test': async_unittest,
       'element_types_test': firefox_fail,
@@ skipping 476 matching lines @@
 
     for (let action of unittest_tests) {
       try {
         action();
       } catch (e) {
         console.error("Caught error tying to setup test:", e);
       }
     }
   });
 });