Minimal fix for Wikibase related SpecialMobileWatchlist fatal

Catchable fatal error:  Argument 5 passed to Wikibase\ClientHooks::onSpecialWatchlistQuery() must be an array, none given in /usr/local/apache/common-local/php-1.21wmf12/extensions/Wikibase/client/WikibaseClient.hooks.php on line 311

Change-Id: Ic4e337c3a22388f52e0a515b4ee3aa7c15381d04
Merge "Minimal fix for Wikibase related SpecialMobileWatchlist fatal"