Fix stale comments around closed type families.

compiler/typecheck/FamInst.lhs

@@ -35,7 +35,7 @@ import Maybes
 import TcMType
 import TcType
 import Name
-import VarSet -- RAE
+import VarSet
 import Control.Monad
 import Data.Map (Map)
 import qualified Data.Map as Map

compiler/types/FamInstEnv.lhs

@@ -784,8 +784,7 @@ findBranch (CoAxBranch { cab_tvs = tpl_tvs, cab_lhs = tpl_lhs, cab_incomps = inc
       Just subst -- matching worked. now, check for apartness.
         |  all (isSurelyApart
                 . tcApartTys instanceBindFun target_tys
-                . coAxBranchLHS) $ -- RAE: This is horribly inefficient
-             incomps
+                . coAxBranchLHS) incomps
         -> -- matching worked & we're apart from all incompatible branches. success
            Just (ind, substTyVars subst tpl_tvs)