Fix polyfill

examples/console/src/index.ts

@@ -44,7 +44,8 @@ import {
   Widget
 } from 'phosphor-widget';
 
-import 'es6-promise';  // Polyfill for IE11
+// ES6 Promise polyfill
+require('es6-promise').polyfill();
 
 import 'jupyter-js-notebook/lib/index.css';
 import 'jupyter-js-notebook/lib/theme.css';

examples/notebook/src/index.ts

@@ -44,7 +44,8 @@ import {
   Widget
 } from 'phosphor-widget';
 
-import 'es6-promise';  // Polyfill for IE11
+// ES6 Promise polyfill
+require('es6-promise').polyfill();
 
 import 'jupyter-js-notebook/lib/index.css';
 import 'jupyter-js-notebook/lib/theme.css';