Typecheck chrome://help using CompilerPass.java, everything except dependency to options

chrome/browser/resources/help/channel_change_page.js

 // Copyright 2013 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('help', function() {
   /**
    * Encapsulated handling of the channel change overlay.
    */
   function ChannelChangePage() {}
 
@@ skipping 75 matching lines @@
       var options = this.getAllChannelOptions_();
       for (var i = 0; i < options.length; i++) {
         var option = options[i];
         if (option.checked)
           option.focus();
       }
     },
 
     /**
      * Returns the list of all radio buttons responsible for channel selection.
-     * @return {Array.<HTMLInputElement>} Array of radio buttons
+     * @return {NodeList} Array of radio buttons
      * @private
      */
     getAllChannelOptions_: function() {
       return $('channel-change-page').querySelectorAll('input[type="radio"]');
     },
 
     /**
      * Returns value of the selected option.
-     * @return {string} Selected channel name or null, if neither
+     * @return {?string} Selected channel name or null, if neither
      *     option is selected.
      * @private
      */
     getSelectedOption_: function() {
       var options = this.getAllChannelOptions_();
       for (var i = 0; i < options.length; i++) {
         var option = options[i];
         if (option.checked)
           return option.value;
       }
@@ skipping 138 matching lines @@
 
   ChannelChangePage.isPageReady = function() {
     return ChannelChangePage.getInstance().isPageReady_();
   };
 
   // Export
   return {
     ChannelChangePage: ChannelChangePage
   };
 });