* Use `assertSame()` instead of `fail()` to display a proper message in case of failure.
* Add an optional `$message` parameter for consistency with other assertions.
Follow-up to [51478], [51479].
See #53363.
git-svn-id: https://develop.svn.wordpress.org/trunk@51480 602fd350-edb4-49c9-b593-d223f7449a82