var path = require('path');

module.exports = {
    entry: path.resolve(__dirname, 'lib', 'client.js'),
    output: {
        filename: 'app.js',
        path: path.resolve(__dirname, 'lib'),
    },
};

@@ -51,16 +51,57 @@
   entry:
+ %5B%0A        'babel-core/polyfill',%0A       
  path.re
@@ -134,24 +134,31 @@
 lient.js'),%0A
+    %5D,%0A
     output: 

Load babel-core/polyfill in the example (thanks to @DylanSale)