Create implementation of the side panel using a dialog.

chrome/test/data/webui/settings/rtl_tests.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.
 
 cr.define('settings_rtl_tests', function() {
   /** @implements {settings.DirectionDelegate} */
   function TestDirectionDelegate(isRtl) {
     /** @override */
     this.isRtl = function() { return isRtl; };
   }
 
   function registerDrawerPanelTests() {
     suite('settings drawer panel RTL tests', function() {
       test('test i18n processing flips drawer panel', function() {
         var ui = document.createElement('settings-ui');
-        var appDrawer = ui.$$('app-drawer');
+        var appDrawer = ui.$.drawer;
         assertEquals('left', appDrawer.align);
 
         ui.directionDelegate = new TestDirectionDelegate(true /* isRtl */);
         assertEquals('right', appDrawer.align);
 
         ui.directionDelegate = new TestDirectionDelegate(false /* isRtl */);
         assertEquals('left', appDrawer.align);
       });
     });
   }
 
   return {
     registerDrawerPanelTests: registerDrawerPanelTests,
   };
 });