Jakub Adam authored Jun 12, 2019 and Matthew Waters committed Jul 29, 2019

When negotiating a data channel, Chrome as recent as 75 still uses SDP
based on version 05 of the SCTP SDP draft, for example:

 m=application 9 DTLS/SCTP 5000
 a=sctpmap:5000 webrtc-datachannel 1024

Implement support for parsing SCTP port out of SDP message with sctpmap
attribute. Fixes data channel negotiation with Chrome browser.