code: function TrEvent(type, opt_bubbles, opt_preventable) {
        var e = tr.doc.createEvent('Event');
        e.initEvent(type, !!opt_bubbles, !!opt_preventable);
        e.__proto__ = global.Event.prototype;
        return e;
      }
docs: Creates a new event to be used with tr.b.EventTarget or DOM EventTarget
  objects.
  @param {string} type The name of the event.
  @param {boolean=} opt_bubbles Whether the event bubbles.
  Default is false.
  @param {boolean=} opt_preventable Whether the default action of the event
  can be prevented.
  @constructor
  @extends {Event}