Remove redundant conditions from the `invocation parameters` definition.

I checked N3866, and the redundancy was there too.  It was there in order to
fit into the INVOKE definition in [func.require], but since the Fundamentals TS
isn't defining INVOKE, we don't need the extra bullets here.
Merge pull request #41 from jyasskin/simplify-invocation-type

Remove redundant conditions from the `invocation parameters` definition.