async createFile(path, name) {
    const result = await this._fsIOService.createFile(this._rootURL + (path.length === 0 || path.startsWith('/') ? '' : '/') + path);
    return result.substr(this._rootURL.length + 1);
  }
@override
@param {string} path
@param {?string} name
@return {!Promise<?string>}