[MD settings] remove unneeded use of I18nBehavior

chrome/browser/resources/settings/controls/settings_dropdown_menu.js

 // Copyright 2015 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.
 
 /**
  * The |name| is shown in the gui.  The |value| us use to set or compare with
  * the preference value.
  * @typedef {{
  *   name: string,
  *   value: (number|string)
@@ skipping 57 matching lines @@
      * The value of the 'custom' item.
      * @private
      */
     notFoundValue_: {
       type: String,
       value: 'SETTINGS_DROPDOWN_NOT_FOUND_ITEM',
     },
   },
 
   behaviors: [
-    I18nBehavior,
     PrefControlBehavior,
   ],
 
   observers: [
     'checkSetup_(menuOptions)',
     'updateSelected_(pref.value)',
   ],
 
   ready: function() {
     this.checkSetup_(this.menuOptions);
@@ skipping 54 matching lines @@
   },
 
   /**
    * @return {boolean}
    * @private
    */
   shouldDisableMenu_: function() {
     return this.disabled || !this.menuOptions.length;
   },
 });