Add Isolate.onExit.

tests/isolate/ondone_test.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:isolate";
+import "dart:async";
+import "package:async_helper/async_helper.dart";
+
+void isomain(SendPort replyPort) {
+  RawReceivePort port = new RawReceivePort();
+  port.handler = (v) {
+    if (v == 0) {
+      // Shut down when receiving the 0 message.
+      port.close();
+    } else {
+      replyPort.send(v);
+    }
+  };
+  replyPort.send(port.sendPort);
+}
+
+void main() {
+  asyncStart();
+  var completer = new Completer();  // Completed by first reply from isolate.
+  RawReceivePort reply = new RawReceivePort(completer.complete);
+  bool mayComplete = false;
+  Isolate.spawn(isomain, reply.sendPort).then((Isolate isolate) {
+    isolate.onExit.then((_) {
+      reply.close();
+      if (!mayComplete) throw "COMPLETED EARLY";
+      asyncEnd();
+    });
+    return completer.future;
+  }).then((echoPort) {
+    int counter = 4;
+    reply.handler = (v) {
+      if (v != counter) throw "WRONG REPLY";
+      if (v == 0) throw "REPLY INSTEAD OF SHUTDOWN";
+      counter--;
+      mayComplete = (counter == 0);
+      echoPort.send(counter);
+    };
+    echoPort.send(counter);
+  });
+}