* Instead of Untouchables being a [Unique], it is simply an Int
  indicating the depth of nesting.  This works fine now that
  floatEqualities is promoting the floated unification variables
  to the outer level

* Remove the inert_tv_eqs (InScopeSet) from InertCans.  It wasn't
  being used.  See Note [Shadowing in a constraint] in TcRnTypes

* Rename inert_frozen to inert_insols

* Some simple refactoring in
     TcErrors.reportFlatsAndInsols
     TcInteract.kickOutRewritable
     TsSimplify.floatEqualities