Update WikimediaEvents for cherry-picks

* Ib44fe0898: Inject 'wgPoweredByHHVM' JS config var if powered by HHVM
* I4958aff23: Tag changes made with HHVM

(Corrects Ie0a55421d.)

Change-Id: If7abf09d9b36c86a9b05ca8d918e6307b84c9d85