static parseColonTimeWithFrames_(rateInfo, text) {
    // 01:02:43:07 ('07' is frames) or 01:02:43:07.1 (subframes)
    const results = shaka.text.TtmlTextParser.timeColonFormatFrames_.exec(text);

    const hours = Number(results[1]);
    const minutes = Number(results[2]);
    let seconds = Number(results[3]);
    let frames = Number(results[4]);
    const subframes = Number(results[5]) || 0;

    frames += subframes / rateInfo.subFrameRate;
    seconds += frames / rateInfo.frameRate;

    return seconds + (minutes * 60) + (hours * 3600);
  }
Parses a TTML colon formatted time containing frames.

@param {!shaka.text.TtmlTextParser.RateInfo_} rateInfo
@param {string} text
@return {?number}
@private