fix(build) require babel-polyfill in production too

website/src/index.js

@@ -4,9 +4,11 @@
 // In production, the es6 code is pre-transpiled so it doesn't need it
 if (process.env.NODE_ENV !== 'production') {
   require('babel-register');
-  require('babel-polyfill');
 }
 
+// The BabelJS polyfill is needed in production too
+require('babel-polyfill');
+
 // Only do the minimal amount of work before forking just in case of a dyno restart
 const cluster = require('cluster');
 const nconf = require('nconf');