inline boxes require a second pass horizontal positioning. non-inline box content is fine with one pass.
Created attachment 448136 [details] Patch
Created attachment 448140 [details] Patch
Committed r287501 (245636@main): <https://commits.webkit.org/245636@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 448140 [details].
<rdar://problem/87040364>