Removed polymer & mirror from Observatory

runtime/observatory/lib/src/elements/retaining_path.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 49 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;
           if (_expanded) {
             e.control.disabled = true;
             await _refresh();
             e.control.disabled = false;
           }
         })
     ];
   }
@@ skipping 37 matching lines @@
     }
 
     content.add(
       anyRef(_isolate, item.source, _instances, queue: _r.queue)
     );
 
     return new DivElement()..classes = ['indent']
             ..children = content;
   }
 }