Fix checked mode service test.

runtime/observatory/lib/src/service/object.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.
 
 part of service;
 
 /// An RpcException represents an exceptional event that happened
 /// while invoking an rpc.
 abstract class RpcException implements Exception {
   RpcException(this.message);
@@ skipping 2815 matching lines @@
 class CodeInlineInterval {
   final int start;
   final int end;
   final List<ServiceFunction> functions = new List<ServiceFunction>();
   bool contains(int pc) => (pc >= start) && (pc < end);
   CodeInlineInterval(this.start, this.end);
 }
 
 class Code extends ServiceObject {
   @observable CodeKind kind;
-  @observable Instance objectPool;
+  @observable ServiceObject objectPool;
   @observable ServiceFunction function;
   @observable Script script;
   @observable bool isOptimized = false;
   @reflectable int startAddress = 0;
   @reflectable int endAddress = 0;
   @reflectable final instructions = new ObservableList<CodeInstruction>();
   @observable ProfileCode profile;
   final List<CodeInlineInterval> inlineIntervals =
       new List<CodeInlineInterval>();
   final ObservableList<ServiceFunction> inlinedFunctions =
@@ skipping 472 matching lines @@
     var v = list[i];
     if ((v is ObservableMap) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is ObservableList) {
       _upgradeObservableList(v, owner);
     } else if (v is ObservableMap) {
       _upgradeObservableMap(v, owner);
     }
   }
 }