static parseFramesTime_(rateInfo, text) {
    // 75f or 75.5f
    const results = shaka.text.TtmlTextParser.timeFramesFormat_.exec(text);
    const frames = Number(results[1]);

    return frames / rateInfo.frameRate;
  }
Parses a TTML time in frame format.

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