js/libs/ember-1.5.1.js
function(obj) {
    var loc = get(this, 'length') || 0;
    while(--loc >= 0) {
      var curObject = this.objectAt(loc) ;
      if (curObject === obj) this.removeAt(loc) ;
    }
    return this ;
  }
function(obj) {
    var loc = get(this, 'length') || 0;
    while(--loc >= 0) {
      var curObject = this.objectAt(loc) ;
      if (curObject === obj) this.removeAt(loc) ;
    }
    return this ;
  }
.......................................................... IMPLEMENT Ember.MutableEnumerable