For some reasons the patch that landed in bug 232422 is incomplete.
rdar://85045948
in bug 232422; only the WebCore parts landed, missing the WebKit ones that actually use SharedMemory
Created attachment 443376 [details] Patch
Comment on attachment 443376 [details] Patch patch got reviewed in bug 232422
Created attachment 443377 [details] [fast-cq] Patch
Committed r285335 (243898@main): <https://commits.webkit.org/243898@main> All reviewed patches have been landed. Closing bug and clearing flags on attachment 443377 [details].