[Cocoa] Delete some text workarounds for bugs in unsupported OSes
<rdar://problem/106957241>
Pull request: https://github.com/WebKit/WebKit/pull/11724
Committed 261891@main (4c7f44ffa855): <https://commits.webkit.org/261891@main> Reviewed commits have been landed. Closing PR #11724 and removing active labels.