We lose overflow from child RenderBoxes.
rdar://74050874
Created attachment 420466 [details] patch
Created attachment 420467 [details] patch
ChangeLog entry in LayoutTests/ChangeLog is not at the top of the file.
Created attachment 420473 [details] patch
Committed r272906: <https://commits.webkit.org/r272906> All reviewed patches have been landed. Closing bug and clearing flags on attachment 420473 [details].