static convertAnalysisToSaveableLanternData(networkAnalysis) {
    /** @type {LH.PrecomputedLanternData} */
    const lanternData = {additionalRttByOrigin: {}, serverResponseTimeByOrigin: {}};
    for (const [origin, value] of networkAnalysis.additionalRttByOrigin.entries()) {
      if (origin.startsWith('http')) lanternData.additionalRttByOrigin[origin] = value;
    }

    for (const [origin, value] of networkAnalysis.serverResponseTimeByOrigin.entries()) {
      if (origin.startsWith('http')) lanternData.serverResponseTimeByOrigin[origin] = value;
    }

    return lanternData;
  }
@param {LH.Artifacts.NetworkAnalysis} networkAnalysis
@return {LH.PrecomputedLanternData}