Summary:
There's no need for us to have a property that can be undefined, since we can use the magic of *passing arguments* to achieve the same end result.
The unit test a bit more precarious, but it's left here for posterity or until we decide to kill it otherwise.
Reviewed By: passy
Differential Revision: D33892407
fbshipit-source-id: 3b499511189862e2265d8d6d29f849a7b813050e
9cbdc3038f