Make EarlyBinder's inner value private; and fix all of the resulting errors

compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs

@@ -148,11 +148,7 @@ pub(in crate::solve) fn instantiate_constituent_tys_for_sized_trait<'tcx>(
 
         ty::Adt(def, substs) => {
             let sized_crit = def.sized_constraint(ecx.tcx());
-            Ok(sized_crit
-                .0
-                .iter()
-                .map(|ty| sized_crit.rebind(*ty).subst(ecx.tcx(), substs))
-                .collect())
+            Ok(sized_crit.subst_iter_copied(ecx.tcx(), substs).collect())
         }
     }
 }