First cut at _spawnUri rpc in the vm service.

sdk/lib/vmservice/message.dart

 // Copyright (c) 2013, 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.
 
 part of dart._vmservice;
 
 class Message {
   final Completer _completer = new Completer.sync();
   bool get completed => _completer.isCompleted;
   /// Future of response.
@@ skipping 112 matching lines @@
   // maintain the list of supported methods below.
   bool _methodNeedsObjectParameters(String method) {
     switch (method) {
       case '_listDevFS':
       case '_listDevFSFiles':
       case '_createDevFS':
       case '_deleteDevFS':
       case '_writeDevFSFile':
       case '_writeDevFSFiles':
       case '_readDevFSFile':
+      case '_spawnUri':
         return true;
       default:
         return false;
     }
   }
 
   Future<String> sendToVM() {
     final receivePort = new RawReceivePort();
     receivePort.handler = (value) {
       receivePort.close();
@@ skipping 32 matching lines @@
   }
 
   void setErrorResponse(int code, String details) {
     _completer.complete(encodeRpcError(this, code,
                                        details: '$method: $details'));
   }
 }
 
 external bool sendIsolateServiceMessage(SendPort sp, List m);
 external void sendRootServiceMessage(List m);
-external void sendObjectRootServiceMessage(List m);
+external void sendObjectRootServiceMessage(List m);