IE11 el-menu鼠标滑过报错：Error in v-on handler: "TypeError: 对象不支持此操作"

考虑到element-ui版本更新或者重新通过npm install安装包时，写入node_moduleselement-uilibelement-ui.common.js里面的patch会失效。

其实可以单独写入一个文件到项目目录里面，然后在webpack的打包入口文件里面，在引入element-ui之前引入。

 1 `(function (window) {
 2 try {
 3 new MouseEvent('test');
 4 return false; // No need to polyfill
 5 } catch (e) {
 6 // Need to polyfill - fall through
 7 }
 8 
 9 // Polyfills DOM4 MouseEvent
10 var MouseEventPolyfill = function (eventType, params) {
11     params = params || { bubbles: false, cancelable: false };
12     var mouseEvent = document.createEvent('MouseEvent');
13     mouseEvent.initMouseEvent(eventType, 
14         params.bubbles,
15         params.cancelable,
16         window,
17         0,
18         params.screenX || 0,
19         params.screenY || 0,
20         params.clientX || 0,
21         params.clientY || 0,
22         params.ctrlKey || false,
23         params.altKey || false,
24         params.shiftKey || false,
25         params.metaKey || false,
26         params.button || 0,
27         params.relatedTarget || null
28     );
29 
30     return mouseEvent;
31 }
32 
33 MouseEventPolyfill.prototype = Event.prototype;
34 
35 window.MouseEvent = MouseEventPolyfill;
36 })(window);`

源码目录 node_moduleselement-uilibelement-ui.common.js
参考 https://github.com/ElemeFE/element/issues/17404