[Media Router WebUI] Run afterNextRender() before tests using media-router-container.

chrome/test/data/webui/media_router/media_router_search_highlighter_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.
 
 /** @fileoverview Suite of tests for media-router-search-highlighter. */
 cr.define('media_router_search_highlighter', function() {
   function registerTests() {
     suite('MediaRouterSearchHighlighter', function() {
       /**
        * Media Router Search Highlighted created before each test.
@@ skipping 28 matching lines @@
         return PolymerTest.importHtml(
             'chrome://media-router/elements/media_router_search_highlighter/' +
             'media_router_search_highlighter.html');
       });
 
       // Initialize a media-router-search-highlighter before each test.
       setup(function(done) {
         PolymerTest.clearBody();
         searchHighlighter =
             document.createElement('media-router-search-highlighter');
+        document.body.appendChild(searchHighlighter);
 
-
-        document.body.appendChild(searchHighlighter);
         // Let the search highlighter be created and attached.
         setTimeout(done);
       });
 
       test('text content correct', function(done) {
         var testInputs = [];
 
         // Both null and '' should be acceptable in the arrays for producing no
         // text.
         var highlightedOnlyMultiple = {
@@ skipping 86 matching lines @@
         });
         done();
       });
     });
   }
 
   return {
     registerTests: registerTests,
   };
 });