The macOS port already allows building `release+assert` but the cmake project didn't expose this. This adds a `-DENABLE_ASSERTS` option to enable with a normal release build.
Pull request: https://github.com/WebKit/WebKit/pull/16526
Committed 266778@main (1ef24965e556): <https://commits.webkit.org/266778@main> Reviewed commits have been landed. Closing PR #16526 and removing active labels.