static getBufferedInfo(b) {
    if (!b) {
      return [];
    }
    const ret = [];
    for (let i = 0; i < b.length; i++) {
      ret.push({start: b.start(i), end: b.end(i)});
    }
    return ret;
  }
@param {TimeRanges} b
@return {!Array<shaka.extern.BufferedRange>}