skip(numBlocks) {
    if (this.pos_ + numBlocks > this.packetData_.length) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.TEXT,
          shaka.util.Error.Code.BUFFER_READ_OUT_OF_BOUNDS);
    }
    this.pos_ += numBlocks;
  }
Skips the provided number of blocks in the buffer.
@param {number} numBlocks
@throws {!shaka.util.Error}