`PlaceholderSynchronizer::inflate_and_enter` currently performs an invalid transition of the markWord away from monitor. This may lead to an ABA issue.

This got opportunistically added at some point to avoid spinning on the deflation thread progress. The issue of guaranteed progress is not something that has been observed as an issue. If guaranteed progress turns out to be required there are solutions which do not have ABA issues, but it requires extra state in the already heavily contested markWord.