Issue #2233623 by Berdir, slashrsm, xjm: Fixed Merge AliasManagerCacheDecorator into AliasManager.
Issue #788900 by ParisLiakos, dawehner, effulgentsia, xjm, et al: Deprecate and remove usages of arg().
Issue #2214209 by dawehner, ParisLiakos, xjm: Move _menu_site_is_offine() into the Maintainance subscriber.