Revert "Rename polymer and cr_elements v0_8 to v1_0"

ui/webui/resources/cr_elements/v0_8/cr_checkbox/cr_checkbox.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.
 
 /**
  * @fileoverview
  * `cr-checkbox` is a button that can be either checked or unchecked. User
  * can tap the checkbox to check or uncheck it. Usually you use checkboxes
  * to allow user to select multiple options from a set. If you have a single
  * ON/OFF option, avoid using a single checkbox and use `cr-toggle-button`
@@ skipping 26 matching lines @@
       type: Boolean,
       value: false,
       reflectToAttribute: true
     },
   },
 
   toggle: function() {
     this.$.checkbox.toggle();
   },
 });