Removed polymer & mirror from Observatory

runtime/observatory/lib/src/elements/strongly_reachable_instances.dart

 // 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.
 
 import 'dart:html';
 import 'dart:async';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/src/elements/curly_block.dart';
 import 'package:observatory/src/elements/instance_ref.dart';
 import 'package:observatory/src/elements/helpers/any_ref.dart';
@@ skipping 53 matching lines @@
   @override
   void detached() {
     super.detached();
     children = [];
     _r.disable(notify: true);
   }
 
   void render() {
     children = [
       new CurlyBlockElement(expanded: _expanded, queue: _r.queue)
-        ..children = _createContent()
+        ..content = _createContent()
         ..onToggle.listen((e) async {
           _expanded = e.control.expanded;
           e.control.disabled = true;
           await _refresh();
           e.control.disabled = false;
         })
     ];
   }
 
   Future _refresh() async {
@@ skipping 32 matching lines @@
       ..text = 'show next ${count}';
     button.onClick.listen((_) async {
       button.disabled = true;
       _result = await _stronglyReachableInstances.get(_isolate, _cls,
                                                       limit: count * 2);
       _r.dirty();
     });
     return [button];
   }
 }