Switch with enum code warnings not consistent with dartpad

[mehmetf]

The following code produces no warnings on dartpad:

enum TestEnum {
  VAL1,
  VAL2
}

int f(TestEnum val) {
  switch (val) {
    case TestEnum.VAL1:
      return 0;
    case TestEnum.VAL2:
      return 1;
  }
}

but with Atom:

Perhaps dartpad does not show "info" level warnings by default but I wanted to highlight this discrepancy.

[eseidelGoogle]

FYI @devoncarew this was a request from Flutter's customer:leafy at our meeting just now.

[devoncarew]

closing this item - re-filed against the sdk repo.