Options: Remove the hidden class, since we override the hidden attribute to set

chrome/browser/resources/options/language_options.js

 // Copyright (c) 2011 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.
 
 // TODO(kochi): Generalize the notification as a component and put it
 // in js/cr/ui/notification.js .
 
 cr.define('options', function() {
   const OptionsPage = options.OptionsPage;
   const LanguageList = options.LanguageList;
@@ skipping 71 matching lines @@
         addLanguageList.addEventListener('click',
             this.handleAddLanguageListClick_.bind(this));
       } else {
         // Listen to add language dialog ok button.
         var addLanguageOkButton = $('add-language-overlay-ok-button');
         addLanguageOkButton.addEventListener('click',
             this.handleAddLanguageOkButtonClick_.bind(this));
 
         // Show experimental features if enabled.
         if (templateData.experimentalSpellCheckFeatures == 'true') {
-          $('auto-spell-correction-option').classList.remove('hidden');
+          $('auto-spell-correction-option').hidden = false;
         }
       }
     },
 
     // The preference is a CSV string that describes preload engines
     // (i.e. active input methods).
     preloadEnginesPref: 'settings.language.preload_engines',
     // The list of preload engines, like ['mozc', 'pinyin'].
     preloadEngines_: [],
     // The preference is a string that describes the spell check
@@ skipping 220 matching lines @@
         // Make it look like a text label.
         uiLanguageButton.className = 'text-button';
         // Remove the event listner.
         uiLanguageButton.onclick = undefined;
       } else if (languageCode in templateData.uiLanguageCodeSet) {
         // If the language is supported as UI language, users can click on
         // the button to change the UI language.
         if (cr.commandLine.options['--bwsi']) {
           // In the guest mode for ChromeOS, changing UI language does not make
           // sense because it does not take effect after browser restart.
-          uiLanguageButton.className = 'hidden';
+          uiLanguageButton.hidden = true;
         } else {
           uiLanguageButton.textContent =
               localStrings.getString('display_in_this_language');
           uiLanguageButton.className = '';
           // Send the change request to Chrome.
           uiLanguageButton.onclick = function(e) {
             chrome.send('uiLanguageChange', [languageCode]);
           }
         }
         if (cr.isChromeOS) {
@@ skipping 421 matching lines @@
   LanguageOptions.uiLanguageSaved = function() {
     $('language-options-ui-language-button').style.display = 'none';
     $('language-options-ui-notification-bar').style.display = 'block';
   };
 
   // Export
   return {
     LanguageOptions: LanguageOptions
   };
 });