addStream (stream) {
    if (this.destroying) return
    if (this.destroyed) throw errCode(new Error('cannot addStream after peer is destroyed'), 'ERR_DESTROYED')
    this._debug('addStream()')

    stream.getTracks().forEach(track => {
      this.addTrack(track, stream)
    })
  }
Add a MediaStream to the connection.
@param {MediaStream} stream