addEventListener(type, listener) {
    if (!type || !listener) {
      return;
    }
    const listeners = this.listeners_ || (this.listeners_ = {});
    const listenersForType = listeners[type] || (listeners[type] = []);
    if (!listenersForType.includes(listener)) {
      listenersForType.push(listener);
    }
  }
@param {string} type Type.
@param {import("../events.js").Listener} listener Listener.