code: function(object) {
          object.on = this.on;
          object.off = this.off;
          object.trigger = this.trigger;
          object._promiseCallbacks = undefined;
          return object;
        }
docs: `RSVP.EventTarget.mixin` extends an object with EventTarget methods. For
  Example:
  
  ```javascript
  var object = {};
  
  RSVP.EventTarget.mixin(object);
  
  object.on("finished", function(event) {
  handle event
  });
  
  object.trigger("finished", { detail: value });
  ```
  
  `EventTarget.mixin` also works with prototypes:
  
  ```javascript
  var Person = function() {};
  RSVP.EventTarget.mixin(Person.prototype);
  
  var yehuda = new Person();
  var tom = new Person();
  
  yehuda.on("poke", function(event) {
  console.log("Yehuda says OW");
  });
  
  tom.on("poke", function(event) {
  console.log("Tom says OW");
  });
  
  yehuda.trigger("poke");
  tom.trigger("poke");
  ```
  
  @method mixin
  @param {Object} object object to extend with EventTarget methods
  @private