In IE 11, while developing we were getting Access Denied errors in traceur.js (or babel.js).
This turns out to being related to routing not working in production builds in IE11.
Kevin Phillips helped us out.
The core of the problem can be found here:
The solution is to install and use the latest version of core-js
npm install --save core-js
modify package.json under system
Then in your main js file (probably app.js)