Fix updating packages map on reload and add a regression 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;
 
 // Some value smaller than the object ring, so requesting a large array
 // doesn't result in an expired ref because the elements lapped it in the
 // object ring.
 const int kDefaultFieldLimit = 100;
@@ skipping 1338 matching lines @@
     }
     if (startPos != null) {
       params['tokenPos'] = startPos;
     }
     if (endPos != null) {
       params['endTokenPos'] = endPos;
     }
     return invokeRpc('getSourceReport', params);
   }
 
-  Future<ServiceMap> reloadSources({String rootLibUri, bool pause}) {
+  Future<ServiceMap> reloadSources(
+      {String rootLibUri, String packagesUri, bool pause}) {
     Map<String, dynamic> params = <String, dynamic>{};
     if (rootLibUri != null) {
       params['rootLibUri'] = rootLibUri;
     }
+    if (packagesUri != null) {
+      params['packagesUri'] = packagesUri;
+    }
     if (pause != null) {
       params['pause'] = pause;
     }
     return invokeRpc('reloadSources', params).then((result) {
       _cache.clear();
       return result;
     });
   }
 
   void _handleIsolateReloadEvent(ServiceEvent event) {
@@ skipping 3250 matching lines @@
     var v = list[i];
     if ((v is Map) && _isServiceMap(v)) {
       list[i] = owner.getFromMap(v);
     } else if (v is List) {
       _upgradeList(v, owner);
     } else if (v is Map) {
       _upgradeMap(v, owner);
     }
   }
 }