Rename MAC_CATALYST_GRAMMAR_CHECKING to ENABLE_POST_EDITING_GRAMMAR_CHECKING for clarity.
Pull request: https://github.com/WebKit/WebKit/pull/1389
Committed r295408 (251414@main): <https://commits.webkit.org/251414@main> Reviewed commits have been landed. Closing PR #1389 and removing active labels.
<rdar://problem/94682618>