static computeUsage(stylesheetInfo) {
    let usedUncompressedBytes = 0;
    const totalUncompressedBytes = stylesheetInfo.content.length;

    for (const usedRule of stylesheetInfo.usedRules) {
      usedUncompressedBytes += usedRule.endOffset - usedRule.startOffset;
    }

    const compressedSize = estimateCompressedContentSize(
        stylesheetInfo.networkRecord, totalUncompressedBytes, 'Stylesheet');
    const percentUnused = (totalUncompressedBytes - usedUncompressedBytes) / totalUncompressedBytes;
    const wastedBytes = Math.round(percentUnused * compressedSize);

    return {
      wastedBytes,
      wastedPercent: percentUnused * 100,
      totalBytes: compressedSize,
    };
  }
@param {StyleSheetInfo} stylesheetInfo
@return {{wastedBytes: number, totalBytes: number, wastedPercent: number}}