First step for fixing Issue 9416.

tests/isolate/spawn_uri_nested_child1_vm_isolate.dart

+// Copyright (c) 2012, 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.
+
+// Example of nested spawning of isolates from a URI
+// Note: the following comment is used by test.dart to additionally compile the
+// other isolate's code.
+library NestedSpawnUriChild1Library;
+import 'dart:isolate';
+import '../../pkg/unittest/lib/unittest.dart';
+
+main() {
+  ReceivePort port2 = new ReceivePort();
+  port2.receive((msg, SendPort replyTo) {
+    port2.close();
+  });
+
+  SendPort s = spawnUri('spawn_uri_nested_child2_vm_isolate.dart');
+  s.send('hi', port2.toSendPort());
+
+  port.receive((message, SendPort replyTo) {
+    var result = message;
+    replyTo.send(result);
+  });
+}