The negative line numbers should only be counting from the last explicit track in each direction. Currently they are being shown as counting from the last track, including implicit tracks.
<rdar://problem/76272817>
Created attachment 425321 [details] Patch v1.0
Comment on attachment 425321 [details] Patch v1.0 r=me
Committed r275558: <https://commits.webkit.org/r275558> All reviewed patches have been landed. Closing bug and clearing flags on attachment 425321 [details].