The browser tests on beta should be stable, so that they can be used to alert people in case of regressions: https://integration.wikimedia.org/ci/job/selenium-Wikibase/BROWSER=firefox,MEDIAWIKI_ENVIRONMENT=beta,PLATFORM=Linux,label=contintLabsSlave%20&&%20UbuntuTrusty/
This is even more important as it's not possible to subscribe to only failures of the test.wikidata.org browser tests right now (which I would like to have, for post-deploy checking).