Fix dart warnings.

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;
 
 /// A [ServiceObject] represents a persistent object within the vm.
 abstract class ServiceObject extends Observable {
   static int LexicalSortName(ServiceObject o1, ServiceObject o2) {
     return o1.name.compareTo(o2.name);
@@ skipping 264 matching lines @@
 
     _update(map, mapIsRef);
   }
 
   // Updates internal state from [map]. [map] can be a reference.
   void _update(ObservableMap map, bool mapIsRef);
 }
 
 abstract class Coverage {
   // Following getters and functions will be provided by [ServiceObject].
-  ServiceObjectOwner get owner;
-  String get type;
-  VM get vm;
+  String get id;
+  Isolate get isolate;
 
   /// Default handler for coverage data.
   void processCoverageData(List coverageData) {
     coverageData.forEach((scriptCoverage) {
       assert(scriptCoverage['script'] != null);
       scriptCoverage['script']._processHits(scriptCoverage['hits']);
     });
   }
 
   Future refreshCoverage() {
     Map params = {};
     if (this is! Isolate) {
       params['targetId'] = id;
     }
     return isolate.invokeRpcNoUpgrade('getCoverage', params).then(
         (ObservableMap map) {
-          var coverageOwner = (type == 'Isolate') ? this : owner;
-          var coverage = new ServiceObject._fromMap(coverageOwner, map);
+          var coverage = new ServiceObject._fromMap(isolate, map);
           assert(coverage.type == 'CodeCoverage');
           var coverageList = coverage['coverage'];
           assert(coverageList != null);
           processCoverageData(coverageList);
         });
   }
 }
 
 abstract class ServiceObjectOwner extends ServiceObject {
   /// Creates an empty [ServiceObjectOwner].
@@ skipping 2538 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);
     }
   }
 }