addEventListener(type, listener, options) {
    if (!this.listeners_) {
      return;
    }
    this.listeners_.push(type, listener);
  }
Add an event listener to this object.

@param {string} type The event type to listen for.
@param {shaka.util.FakeEventTarget.ListenerType} listener The callback or
  listener object to invoke.
@param {(!AddEventListenerOptions|boolean)=} options Ignored.
@override
@exportInterface