pkg/front_end/testcases/inference/promotion_subtype_check.dart:9:9: Context: Possible promotion of x@276
  if (x is int) {
        ^^
pkg/front_end/testcases/inference/promotion_subtype_check.dart:10:36: Context: Possible promotion of x@276
    if (/*@ promotedType=int* */ x is String) {
                                   ^^
pkg/front_end/testcases/inference/promotion_subtype_check.dart:18:9: Context: Possible promotion of x@276
  if (x is String) {
        ^^