Review other uses of "stopped"

[aboba]

The following references to "stopped" RtpSender/RtpReceivers need to be reviewed:

1. Definition of close():
   All RTCRtpSenders in senders are now considered stopped.
   All RTCRtpReceivers in receivers are now considered stopped.
   Could we instead set RTCRtpTransceiver.stopped to true?

2. replaceTrack:
   If sender is stopped, return a promise rejected with an InvalidStateError.
   Could we instead test if transceiver.stopped is true?

3. insertDTMF:
   If sender has been stopped, throw an InvalidStateError exception.
   If sender has been stopped, abort these steps.
   Could we test if transceiver.stopped is true or if transceiver.direction is recvonly?

[taylor-b]

All those suggestions sound right to me. Though for insertDTMF, the direction could be "recvonly" or "inactive". And I assume it's really the SDP-negotiated direction that matters, not just the last value you passed into setDirection.

[aboba]

@taylor-b It makes sense to not allow insertDTMF on a sender that cannot send and I agree that we need the SDP-negotiated direction to determine this (or maybe encodings[].active??), not transceiver.direction.