Quick sidequestion: Does HHVM support the Weakref extension?

I ask because while it is not listed on the github wiki[1] but does appear in the manual[2]. I'm assuming the manual is an oversight, branched from PHP's manual and not pruned.

That said, weak-references are indispensable for certain problems, and I'd love to see them standard.

[1] https://github.com/facebook/hhvm/wiki/Extensions [2] http://docs.hhvm.com/manual/en/book.weakref.php