title: How to use ES6 Hash Map on any object without maintaing a reference (I.e. Java hashcode)
body: <p>I've been experimenting with ES6 Map in io.js and realized that I can't do the following:</p>
  
  <pre><code>var map = new Map()
  map.set( {key:"value"}, "some string");
  map.get( {key:"value"} ); // undefined. I want "some string"
  </code></pre>
  
  <p>This is because {key:"value"} === {key:"value"} is false.</p>
  
  <p>I need to be able to use an object as a key but not require the ACTUAL object to lookup the value like how java HashMap uses hashcode and equals. Is this possible?</p>