constructor(reportUIFeatures, dom, callbacks) {
    this._reportUIFeatures = reportUIFeatures;
    this._dom = dom;
    this._localeSelectedCallback = callbacks.onLocaleSelected;
  }
@param {ReportUIFeatures} reportUIFeatures
@param {DOM} dom
@param {{onLocaleSelected: (localeModuleName: LH.Locale) => Promise<void>}} callbacks
       Specifiy the URL where the i18n module script can be found, and the URLS for the locale JSON files.