Expose isColumnHeaderCell and isRowHeaderCell through AXCoreObject.
Created attachment 399406 [details] Patch
Created attachment 399412 [details] Patch
fix for iOS build.
Created attachment 399434 [details] Patch
Fix for GTK build.
Committed r261729: <https://trac.webkit.org/changeset/261729> All reviewed patches have been landed. Closing bug and clearing flags on attachment 399434 [details].
<rdar://problem/63253987>