Finish moving service protocol to json rpc.

runtime/observatory/bin/shell.dart

 // Copyright (c) 2014, 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 shell;
 
 import 'package:observatory/service_io.dart';
 
 import 'dart:io';
 
@@ skipping 11 matching lines @@
   // TODO(turnidge): use the non-deprecated api here.
   vm.getStringDeprecated(prefix + stdin.readLineSync()).then((String result) {
     repl(vm, prefix, result);
   });
 }
 
 void main() {
   String addr = 'ws://localhost:8181/ws';
   new WebSocketVM(new WebSocketVMTarget(addr)).load().then((VM vm) {
     Isolate isolate = vm.isolates.first;
-    String prefix = '${isolate.link}';
+    String prefix = '/${isolate.id}';
     repl(vm, prefix, 'prefix $prefix');
   });
 }