title: How to serve different web component to IE 11
body: <p>I've configured my "polymer build" (v 2.0) to transpile an ES5 version just for IE 11, but now I need to serve only that version for IE 11 users and the ES6 version for all other browsers. What's the best way to achieve this? </p>
  
  <p>Ideally, I'd like to use just one import in whichever client pages use my custom element and have some logic on the server to dish out the appropriate version, but being a newbie to web components, I don't want roll my own solution (which will probably be nasty) if there's a "right way" of doing it (so far I haven't found it, but I'll keep searching).</p>
  
  <p>Thanks.</p>