Fix for issue 23244

tests/language/issue23244_test.dart

+import 'dart:async';
+import 'dart:isolate';
+
+enum Fisk {
+  torsk,
+}
+
+isolate1(SendPort port) {
+  port.send(Fisk.torsk);
+}
+
+isolate2(SendPort port) {
+  port.send([Fisk.torsk]);
+}
+
+isolate3(SendPort port) {
+  var x = new Map<int, Fisk>();
+  x[0] = Fisk.torsk;
+  x[1] = Fisk.torsk;
+  port.send(x);
+}
+
+main() async {
+  var port = new ReceivePort();
+  await Isolate.spawn(isolate1, port.sendPort);
+  Completer completer1 = new Completer();
+  port.listen((message) {
+    print("Received $message");
+    port.close();
+    expectTorsk(message);
+    completer1.complete();
+  });
+  await completer1.future;
+  Completer completer2 = new Completer();
+  port = new ReceivePort();
+  await Isolate.spawn(isolate2, port.sendPort);
+  port.listen((message) {
+    print("Received $message");
+    port.close();
+    expectTorsk(message[0]);
+    completer2.complete();
+  });
+  await completer2.future;
+  port = new ReceivePort();
+  await Isolate.spawn(isolate3, port.sendPort);
+  port.listen((message) {
+    print("Received $message");
+    port.close();
+    expectTorsk(message[0]);
+    expectTorsk(message[1]);
+  });
+}
+
+expectTorsk(Fisk fisk) {
+  if (fisk != Fisk.torsk) {
+    throw "$fisk isn't a ${Fisk.torsk}";
+  }
+}
+