Use QuantifiedWhereClause in generic_predicates as well

Still far too much binder skipping going on; I find it hard to imagine
this is all correct, but the tests pass.

crates/hir/src/display.rs

@@ -236,11 +236,7 @@ impl HirDisplay for TypeParam {
         write!(f, "{}", self.name(f.db))?;
         let bounds = f.db.generic_predicates_for_param(self.id);
         let substs = Substitution::type_params(f.db, self.id.parent);
-        let predicates = bounds
-            .iter()
-            .cloned()
-            .map(|b| hir_ty::Binders::new(0, b.subst(&substs)))
-            .collect::<Vec<_>>();
+        let predicates = bounds.iter().cloned().map(|b| b.subst(&substs)).collect::<Vec<_>>();
         if !(predicates.is_empty() || f.omit_verbose_types()) {
             write_bounds_like_dyn_trait_with_prefix(":", &predicates, f)?;
         }