Updated mediawiki/extensions
Project: mediawiki/extensions/VisualEditor  846414f215f50fb7a09e516ce9c89c7992b7c1cc

Destroy test surfaces

Also make sure surface observers are detached so they don't try to
poll the CE when it has been destroyed. This was causing exceptions
to be thrown in test runners.

Change-Id: Ic8864a73f3ee04da6018f552b1aa68748d7ffba7