static isBufferNegligible_(b) {
    // Workaround Safari bug: https://bit.ly/2trx6O8
    // Firefox may leave <1e-4s of data in buffer after clearing all content
    return b.length == 1 && b.end(0) - b.start(0) < 1e-4;
  }
Returns whether the buffer is small enough to be ignored.

@param {TimeRanges} b
@return {boolean}
@private