Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  b67b6e8c55a3a1c5b2c6fc3a9bdd148d0899046d

Browsertests: minor fixes to tags and sitelinks.feature

Added @wikidata.beta.wmflabs.org tag to sitelinks.feature, means that
sitelink tests will now also run regularely on beta.

Introduced a new tag @performance_testing for easy grouping of performance
related tests.

Change-Id: Ifef2d2fc286a0060d03096074a352db967131bb0