When trying the record a timeline in the HTTP inspector, things don't work properly. The bars indicating the different events duration are not showing as in the normal inspector. In order to reproduce this, just go tht timelines tab in the inspector and start a recording.
Created attachment 460371 [details] Patch
Committed r295724 (251729@main): <https://commits.webkit.org/251729@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 460371 [details].