Reduce PGM Metadata Storage from 64 to 40 bytes per allocation
Pull request: https://github.com/WebKit/WebKit/pull/11128
Committed 261305@main (0014f22cde49): <https://commits.webkit.org/261305@main> Reviewed commits have been landed. Closing PR #11128 and removing active labels.
<rdar://problem/106343697>