Do not assert that hidden types don't have erased regions.

Author: cjgillot

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -3116,9 +3116,6 @@ fn bind_generator_hidden_types_above<'tcx>(
  bty.instantiate(tcx, args)
 })
 .collect();
-if considering_regions {
-debug_assert!(!hidden_types.has_erased_regions());
-}
 let bound_vars =
  tcx.mk_bound_variable_kinds_from_iter(bound_vars.iter().chain(
 (num_bound_variables..counter).map(|_| ty::BoundVariableKind::Region(ty::BrAnon)),