js/libs/ember-1.5.1.js
function(array, item) {
    var index = utils.indexOf(array, item);
    if (index === -1) { array.push(item); }
  }
function(array, item) {
    var index = utils.indexOf(array, item);
    if (index === -1) { array.push(item); }
  }
Adds an object to an array. If the array already includes the object this
method has no effect.

@method addObject
@param {Array} array The array the passed item should be added to
@param {Object} item The item to add to the passed array

@return 'undefined'