Roll performance-oriented iron-list changes

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

 // Copyright 2016 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 Suite of tests for settings-languages-page. */
 
 /** @const {string} Path to root from chrome/test/data/webui/settings/. */
 var ROOT_PATH = '../../../../../';
 
 // Polymer BrowserTest fixture.
@@ skipping 95 matching lines @@
       var dialog;
       var dialogItems;
       var cancelButton;
       var actionButton;
 
       setup(function(done) {
         var addLanguagesButton =
             languagesCollapse.querySelector('.list-button:last-of-type');
         MockInteractions.tap(addLanguagesButton);
 
-        // The page stamps the dialog and registers listeners asynchronously.
-        Polymer.Base.async(function() {
+        // The page stamps the dialog, registers listeners, and populates the
+        // iron-list asynchronously at microtask timing, so wait for a new task.
+        setTimeout(function() {
           dialog = languagesPage.$$('settings-add-languages-dialog');
           assertTrue(!!dialog);
 
           actionButton = assert(dialog.$$('.action-button'));
           cancelButton = assert(dialog.$$('.cancel-button'));
 
           // The fixed-height dialog's iron-list should stamp far fewer than
           // 50 items.
           dialogItems =
               dialog.$.dialog.querySelectorAll('.list-item:not([hidden])');
@@ skipping 158 matching lines @@
         assertTrue(!!languagesPage.$$('settings-edit-dictionary-page'));
       }
     });
   }.bind(this));
 
   // TODO(michaelpg): Test more aspects of the languages UI.
 
   // Run all registered tests.
   mocha.run();
 });