pkg/front_end/testcases/inference/for_loop_empty_condition.dart:9:43: Context: Write to x@287
  for (num x = 0;; x /*@ target=num::+ */ ++) {
                                          ^^
pkg/front_end/testcases/inference/for_loop_empty_condition.dart:11:11: Context: Possible promotion of x@287
    if (x is int) {
          ^^