title: PhantomJs: Can't find variable map
body: <p>I receive the following error:</p>
  
  <pre><code>INFO [karma]: Karma v0.13.9 server started at http://localhost:9018/
  
  INFO [launcher]: Starting browser PhantomJS
  
  PhantomJS 1.9.8 (Mac OS X 0.0.0) ERROR
        ReferenceError: Can't find variable: Map
        at /Users/runtimeZero/code/vendor/inert/inert.min.js:589
  </code></pre>
  
  <p>I understand that I am including a file called <a href="https://raw.githubusercontent.com/WICG/inert/master/dist/inert.js" rel="noreferrer">inert.js</a> 
  which is using ES6 Map() . This is freaking out PhantomJs.</p>
  
  <p>So I included core-js/es6/map.js polyfill in my karma config under files. 
  However that does not resolve the issue.</p>
  
  <p>Any tips ?</p>