UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.89 Safari/537.36

Steps to reproduce the problem:
Start Chrome with the following flag:

    --enable-blink-features=RTCRtpSender

Then try this JSFiddle: https://jsfiddle.net/o2w181zr/

In it, we

1. Negotiate once with an SDP that represents a MediaStream ("stream") containing a single audio MediaStreamTrack ("track1").
2. Re-negotiate with an SDP that represents the same MedaiStream, now containing a single audio MediaStreamTrack ("track2").

Note: this should be reproducible even without removing the original "track1" MediaStreamTrack.

What is the expected behavior?
Two RTCTrackEvents are raised on the RTCPeerConnection.

What went wrong?
One RTCTrackEvent is raised on the RTCPeerConnection.

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 62.0.3202.89  Channel: stable
OS Version: OS X 10.12.6
Flash Version: 

Apologies in advance if this is a duplicate of https://bugs.chromium.org/p/chromium/issues/detail?id=774303 -- I did not see this case explicitly called out.