Update charted to 0.4.8 and roll

packages/observable/lib/src/property_change_record.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2016, 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 observe.src.change_record;
+library observable.src.property_change_record;
 
-import 'package:observe/observe.dart';
+import 'change_record.dart';
 
-
-/// Records a change to an [Observable].
-// TODO(jmesserly): remove this type
-abstract class ChangeRecord {}
-
-/// A change record to a field of an observable object.
+/// A change record to a field of an [Observable] object.
 class PropertyChangeRecord<T> extends ChangeRecord {
   /// The object that changed.
-  final object;
+  final Object object;
 
   /// The name of the property that changed.
   final Symbol name;
 
   /// The previous value of the property.
   final T oldValue;
 
   /// The new value of the property.
   final T newValue;
 
   PropertyChangeRecord(this.object, this.name, this.oldValue, this.newValue);
 
   String toString() =>
       '#<PropertyChangeRecord $name from: $oldValue to: $newValue>';
 }