Register existing isolates when service isolate is started

runtime/vm/service/vmservice.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.
 
 library vmservice;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:isolate';
 import 'dart:typed_data';
@@ skipping 76 matching lines @@
     }
     return message.sendToVM();
   }
 }
 
 RawReceivePort boot() {
   // Boot the VMService.
   // Return the port we expect isolate startup and shutdown messages on.
   return new VMService().receivePort;
 }
+
+void _registerIsolate(int port_id, SendPort sp, String name) {
+  var service = new VMService();
+  service.runningIsolates.isolateStartup(port_id, sp, name);
+}