Updated mediawiki/extensions
Project: mediawiki/extensions/Math  94ded6c7b9c2645550cf621a09cd6776fc5d03e4

Port browser test for Math extension from the /qa/browsertest repo

From an earlier discussion with physikerwelt.

This is one step toward retiring the /qa/browsertest repo
entirely.

Change-Id: I804f32d2a5a984c8eb0dfc50c8ab50a7f1035256