In a declared type we need to distinguish between Inferred
and Specified type variables. This was exposed by Trac #15592.

See Note [Work out final tyConBinders] in TcTyClsDecls.

I had to change the definition of HasField in GHC.Records to
   class HasField x r a | x r -> a where
so as to have an /inferred/ kind argument rather than a
specfied one.  So
   HasField :: forall {k}. k -> * -> * -> Constraint