title: how to resolve 'this is not defined' when extending EventEmitter?
body: <p>The following code fails: </p>
  
  <pre><code>var EventEmitter = require('events'); 
  
  class Foo extends EventEmitter{
      constructor(){
          this.name = 'foo';
      }
      print(){
          this.name = 'hello';
          console.log('world');
      }
  }
  var f = new Foo();
  console.log(f.print());
  </code></pre>
  
  <p>and prints error</p>
  
  <pre class="lang-none prettyprint-override"><code> this.name = 'foo';
      ^
  
  ReferenceError: this is not defined
  </code></pre>
  
  <p>However when I am not extending EventEmitter it works fine. </p>
  
  <p>Why is this happening and how can I resolve it? 
  running nodejs 4.2.1</p>