MD History: Lazily load element files which are not needed for first paint

chrome/test/data/webui/md_history/history_routing_test.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('md_history.history_routing_test', function() {
   function registerTests() {
     suite('routing-test', function() {
       var app;
       var list;
       var toolbar;
@@ skipping 67 matching lines @@
   }
   return {
     registerTests: registerTests
   };
 });
 
 cr.define('md_history.history_routing_test_with_query_param', function() {
   function registerTests() {
     suite('routing-with-query-param', function() {
       var app;
-      var list;
       var toolbar;
       var expectedQuery;
 
       suiteSetup(function() {
         app = $('history-app');
-        sidebar = app.$['side-bar']
         toolbar = app.$['toolbar'];
         expectedQuery = 'query';
       });
 
       test('search initiated on load', function(done) {
         var verifyFunction = function(info) {
           assertEquals(expectedQuery, info[0]);
           flush().then(function() {
             assertEquals(
                 expectedQuery,
                 toolbar.$['main-toolbar'].getSearchField().getValue());
             done();
           });
         };
 
         if (window.historyQueryInfo) {
           verifyFunction(window.historyQueryInfo);
           return;
         }
 
         registerMessageCallback('queryHistory', this, verifyFunction);
       });
     });
   }
   return {
     registerTests: registerTests
   };
 });