fix #1748 in IE11 error

src/index.ejs

@@ -7,6 +7,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>Ant Design Pro</title>
   <link rel="icon" href="/favicon.png" type="image/x-icon">
+  <script src="https://cdn.polyfill.io/v2/polyfill.min.js"></script>
   <script src="https://gw.alipayobjects.com/os/rmsportal/nGVBgVyXzzmbAqevIAPy.js">
   </script>
   <script src=" https://gw.alipayobjects.com/os/rmsportal/TKSqiyoUxzrHoMwjViwA.js "></script>