These are corner cases in
   17eb2419 Refactor computing dependent type vars
and I couldn't even come up with a test case

* In TcSimplify.simplifyInfer, in the promotion step, be sure
  to promote kind variables as well as type variables.

* In TcType.spiltDepVarsOfTypes, the CoercionTy case, be sure
  to get the free coercion variables too.