pkg/front_end/testcases/nnbd/intersection_types.dart:13:11: Context: Possible promotion of t@403
    if (t is B?) {
          ^^
pkg/front_end/testcases/nnbd/intersection_types.dart:15:13: Context: Possible promotion of t@403
      if (t is C?) {
            ^^
pkg/front_end/testcases/nnbd/intersection_types.dart:22:11: Context: Possible promotion of t@403
    if (t is B) {
          ^^
pkg/front_end/testcases/nnbd/intersection_types.dart:24:13: Context: Possible promotion of t@403
      if (t is C) {
            ^^