Updated mediawiki/extensions
Project: mediawiki/extensions/Wikibase  840f9c789d0f123087ebece242de6c1f6306a495

Eliminated wikibase.utilities.ui.StatableObject

Since the increased complexity of wikibase.utilities.ui.StatableObject is not required anymore,
the functionality is replaced by native jQuery.Widget handling.
Removing wikibase.utilities.ui.StatableObject renders wikibase.utilities.newExtension useless.
Consequently, the component is removed as well.

Change-Id: I0ff5a3949d3e5218e54d53e6a2c19d465f30eb86