Fixed a11y tab-handling for language settings

chrome/browser/resources/options/deletable_item_list.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 List = cr.ui.List;
   /** @const */ var ListItem = cr.ui.ListItem;
 
   /**
    * Creates a deletable list item, which has a button that will trigger a call
@@ skipping 36 matching lines @@
 
       this.closeButtonElement_ = this.ownerDocument.createElement('button');
       this.closeButtonElement_.className =
           'raw-button row-delete-button custom-appearance';
       this.closeButtonElement_.addEventListener('mousedown',
                                                 this.handleMouseDownUpOnClose_);
       this.closeButtonElement_.addEventListener('mouseup',
                                                 this.handleMouseDownUpOnClose_);
       this.closeButtonElement_.addEventListener('focus',
                                                 this.handleFocus_.bind(this));
+      this.closeButtonElement_.tabIndex = -1;
       this.closeButtonElement_.title =
           loadTimeData.getString('deletableItemDeleteButtonTitle');
       this.appendChild(this.closeButtonElement_);
     },
 
     /**
      * Returns the element subclasses should add content to.
      * @return {HTMLElement} The element subclasses should popuplate.
      */
     get contentElement() {
@@ skipping 120 matching lines @@
      */
     deleteItemAtIndex: function(index) {
     },
   };
 
   return {
     DeletableItemList: DeletableItemList,
     DeletableItem: DeletableItem,
   };
 });