static getFullPageScreenshot(lhr) {
    if (lhr.fullPageScreenshot) {
      return lhr.fullPageScreenshot;
    }

    // Prior to 10.0.
    const details = /** @type {LH.Result.FullPageScreenshot=} */ (
      lhr.audits['full-page-screenshot']?.details);
    return details;
  }
@param {LH.Result} lhr
@return {LH.Result.FullPageScreenshot=}