_registerIconHandler(event) {
    let imgUrl;

    if (!isSupportFileApi) {
      alert('This browser does not support file-api');
    }

    const [file] = event.target.files;

    if (file) {
      imgUrl = URL.createObjectURL(file);
      this.actions.registerCustomIcon(imgUrl, file);
    }
  }
register icon
@param {object} event - file change event object
@private