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。

`(function (window) {
try {
new MouseEvent('test');
return false; // No need to polyfill
} catch (e) {
// Need to polyfill - fall through
}

// Polyfills DOM4 MouseEvent
var MouseEventPolyfill = function (eventType, params) {
    params = params || { bubbles: false, cancelable: false };
    var mouseEvent = document.createEvent('MouseEvent');
    mouseEvent.initMouseEvent(eventType, 
        params.bubbles,
        params.cancelable,
        window,
        0,
        params.screenX || 0,
        params.screenY || 0,
        params.clientX || 0,
        params.clientY || 0,
        params.ctrlKey || false,
        params.altKey || false,
        params.shiftKey || false,
        params.metaKey || false,
        params.button || 0,
        params.relatedTarget || null
    );

    return mouseEvent;
}

MouseEventPolyfill.prototype = Event.prototype;

window.MouseEvent = MouseEventPolyfill;
})(window);`

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