https://www.w3.org/TR/CSS22/tables.html A "missing cell" is a cell in the row/column grid that is not occupied by an element or pseudo-element. Missing cells are rendered as if an anonymous table-cell box occupied their position in the grid.
<rdar://problem/60458806>
Created attachment 393593 [details] Patch
Comment on attachment 393593 [details] Patch Clearing flags on attachment: 393593 Committed r258473: <https://trac.webkit.org/changeset/258473>
All reviewed patches have been landed. Closing bug.