Implement last baseline for alignment properties. This may be able to reuse much of the work from 243523.
<rdar://problem/98089709>
Pull request: https://github.com/WebKit/WebKit/pull/4999
Committed 255455@main (7545fa38ae64): <https://commits.webkit.org/255455@main> Reviewed commits have been landed. Closing PR #4999 and removing active labels.