Add getClassList RPC

runtime/observatory/test/classes_test.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.
 
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 
 var tests = [
 
 (Isolate isolate) =>
+  isolate.getClassHierarchy().then((Class o) {
+    expect(o.name, equals('Object'));
+}),
+
+(Isolate isolate) =>
   isolate.get('classes/62').then((Class c) {
     expect(c.name, equals('_List'));
     expect(c.vmCid, equals(62));
 }),
 
+
 ];
 
 main(args) => runIsolateTests(args, tests);