* Follow-up r90749

* Follow-up r90749
** Tweaked addAutopromoteOnceGroups() calls for performance
** Some doc tweaks and fixes
* Added NS_SPECIAL short-circuit on $wgTitle for file cache and removed unnecessary "is null" check
* Pushed "$action != 'raw'" check into HTMLFileCache
* Removed useless return value from performRequest()
* Added type hint to performAction()