_fireEvent(eventType) {
    const document = this.element.ownerDocument;
    const window = document.defaultView;
    if (typeof window.CustomEvent === 'function') {
      this.element.dispatchEvent(new window.CustomEvent(eventType, {}));
    } else {
      const event = document.createEvent('Event');
      event.initEvent(eventType, false, false);
      this.element.dispatchEvent(event);
    }
  }
Fires event on the element

@param {string} eventType
@private