this is about offsetWidth etc.
Created attachment 445374 [details] Patch
Created attachment 445664 [details] Patch
Created attachment 445725 [details] Patch
Committed r286529 (244861@main): <https://commits.webkit.org/244861@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 445725 [details].
<rdar://problem/86051777>