Compile chrome://settings, part 2: reduce from 950 to 400 errors

chrome/browser/resources/options/options_page.js

 // Copyright (c) 2012 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('options', function() {
   /** @const */ var FocusOutlineManager = cr.ui.FocusOutlineManager;
-  /** @const */ var PageManager = cr.ui.pageManager.PageManager;
 
   var OptionsPage = {
     /**
      * This is the absolute difference maintained between standard and
      * fixed-width font sizes. Refer http://crbug.com/91922.
      * @const
      */
     SIZE_DIFFERENCE_FIXED_STANDARD: 3,
 
     /**
      * Initializes the complete options page. This will cause all C++ handlers
      * to be invoked to do final setup.
      */
     initialize: function() {
       chrome.send('coreOptionsInitialize');
     },
 
     /**
      * Shows the tab contents for the given navigation tab.
-     * @param {!Element} tab The tab that the user clicked.
+     * @param {Node} tab The tab that the user clicked.
      */
     showTab: function(tab) {
       // Search parents until we find a tab, or the nav bar itself. This allows
       // tabs to have child nodes, e.g. labels in separately-styled spans.
-      while (tab && !tab.classList.contains('subpages-nav-tabs') &&
+      while (tab && tab.classList &&
+             !tab.classList.contains('subpages-nav-tabs') &&
              !tab.classList.contains('tab')) {
         tab = tab.parentNode;
       }
-      if (!tab || !tab.classList.contains('tab'))
+      if (!tab || !tab.classList || !tab.classList.contains('tab'))
         return;
 
       // Find tab bar of the tab.
       var tabBar = tab;
-      while (tabBar && !tabBar.classList.contains('subpages-nav-tabs')) {
+      while (tabBar && tabBar.classList &&
+             !tabBar.classList.contains('subpages-nav-tabs')) {
         tabBar = tabBar.parentNode;
       }
-      if (!tabBar)
+      if (!tabBar || !tabBar.classList)
         return;
 
       if (tabBar.activeNavTab != null) {
         tabBar.activeNavTab.classList.remove('active-tab');
         $(tabBar.activeNavTab.getAttribute('tab-contents')).classList.
             remove('active-tab-contents');
       }
 
       tab.classList.add('active-tab');
       $(tab.getAttribute('tab-contents')).classList.add('active-tab-contents');
@@ skipping 47 matching lines @@
     isSettingsApp: function() {
       return document.documentElement.classList.contains('settings-app');
     },
   };
 
   // Export
   return {
     OptionsPage: OptionsPage
   };
 });