horizontal-tb/horizontal-bt/vertical-lr/vertical-rl are marked unimplemented for some reason. Noticed while working on bug 166941.
Created attachment 447977 [details] [fast-cq] Patch
Committed r287446 (245581@main): <https://commits.webkit.org/245581@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 447977 [details].
<rdar://problem/86919782>