Fix CrSettingsLanguagesPageTest dialog flake

chrome/test/data/webui/settings/cr_settings_browsertest.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** @fileoverview Runs the Polymer Settings tests. */
 
 /** @const {string} Path to source root. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 1252 matching lines @@
 function CrSettingsLanguagesTest() {}
 
 CrSettingsLanguagesTest.prototype = {
   __proto__: CrSettingsBrowserTest.prototype,
 
   /** @override */
   browsePreload: 'chrome://md-settings/languages_page/languages.html',
 
   /** @override */
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
+    ROOT_PATH + 'ui/webui/resources/js/promise_resolver.js',
     '../fake_chrome_event.js',
     'test_util.js',
     'test_browser_proxy.js',
     'fake_language_settings_private.js',
     'fake_settings_private.js',
     'fake_input_method_private.js',
     'test_languages_browser_proxy.js',
     'languages_tests.js',
   ]),
 };
@@ skipping 367 matching lines @@
   extraLibraries: CrSettingsBrowserTest.prototype.extraLibraries.concat([
     'test_browser_proxy.js',
     'test_extension_control_browser_proxy.js',
     'extension_controlled_indicator_tests.js',
   ]),
 };
 
 TEST_F('CrSettingsExtensionControlledIndicatorTest', 'All', function() {
   mocha.run();
 });