This is problematic for several reasons:

* Code that we release as source, and developers compile into their apps, shouldn't be using our internal APIs.
* Re-declaring the same property in two places (here and CBLInternal.h) is fragile and non-DRY.
* This declaration is actually wrong: the property type is `CBL_Revision` not `CBLRevision`.

If you need to use `winningRevision` -- and I'm not sure you do -- then we should make it a public property.