Removed Polymer from Observatory deps

packages/polymer_expressions/example/person.dart

-// Copyright (c) 2013, 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 person;
-
-import 'package:observe/observe.dart';
-
-class Person extends ChangeNotifier {
-  String _firstName;
-  String _lastName;
-  List<String> _items;
-
-  Person(this._firstName, this._lastName, this._items);
-
-  String get firstName => _firstName;
-
-  void set firstName(String value) {
-    _firstName = notifyPropertyChange(#firstName, _firstName, value);
-  }
-
-  String get lastName => _lastName;
-
-  void set lastName(String value) {
-    _lastName = notifyPropertyChange(#lastName, _lastName, value);
-  }
-
-  String getFullName() => '$_firstName $_lastName';
-
-  List<String> get items => _items;
-
-  void set items(List<String> value) {
-    _items = notifyPropertyChange(#items, _items, value);
-  }
-
-  String toString() => "Person(firstName: $_firstName, lastName: $_lastName)";
-}