Note: this contains a b/c incompatible change to
SlotRoleHandler, but it's never used in any extensions
and never was used.
Change-Id: I898ab18467f7f8c605a579cc6236859b9d86c7f5
Use one line instead of three to document variable types.
Make ContentHandlerFactory final again, no need to make
non-final.
Use MockServiceDependenciesTrait to simplify creation
of PageUpdaterFactory in unit tests.
Use Wikimedia\Rdbms\LoadBalancer instead of deprecated
alias \LoadBalancer.
Follow-up: I2a060bfa8ac098edf24fc4d51212eeb7ddf3942d
Change-Id: I63b18f71cb6e40c971511e71e8475d49ef530d71
