Dart2js: Fix object leaking between isolates.

tests/isolate/object_leak_test.dart

Index: tests/isolate/object_leak_test.dart
diff --git a/tests/isolate/object_leak_test.dart b/tests/isolate/object_leak_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..4511b43fd99bfe74285ccb437f40588c55e85c14
--- /dev/null
+++ b/tests/isolate/object_leak_test.dart
@@ -0,0 +1,40 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for http://dartbug.com/18942
+
+library LeakTest;
+import "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+import 'dart:isolate';
+import 'dart:async';
+
+
+class A {
+  var x = 0;
+}
+
+fun(msg) {
+  print("received: ${msg.x}");
+  msg.x = 1;
+  print("done updating: ${msg.x}");
+}
+
+main() {
+  asyncStart();
+  var a = new A();
+  // Sending an A object to another isolate should not work.
+  Isolate.spawn(fun, a).then((isolate) {
+    new Timer(const Duration(milliseconds: 300), () {
+      // Changes in other isolate must not reach here.
+      Expect.equals(0, a.x);
+      asyncEnd();
+    });
+  }, onError: (e) {
+    // Sending an A isn't required to work.
+    // It works in the VM, but not in dart2js.
+    print("Send of A failed:\n$e");
+    asyncEnd();
+  });
+}