Wrapping leaf nodes in non polymer elements

runtime/observatory/lib/src/elements/nav/library_menu_wrapper.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 'package:observatory/app.dart';
+import 'package:observatory/service.dart';
+import 'package:observatory/src/elements/helpers/tag.dart';
+import 'package:observatory/src/elements/shims/binding.dart';
+import 'package:observatory/src/elements/nav/library_menu.dart';
+
+class NavLibraryMenuElementWrapper extends HtmlElement {
+  static final binder = new Binder<NavLibraryMenuElementWrapper>(
+    const [const Binding('last'), const Binding('library')]);
+
+  static const tag =
+    const Tag<NavLibraryMenuElementWrapper>('library-nav-menu');
+
+  bool _last = false;
+  Library _library;
+  bool get last => _last;
+  Library get library => _library;
+  set last(bool value) {
+    _last = value; render();
+  }
+  set library(Library value) {
+    _library = value; render();
+  }
+
+  NavLibraryMenuElementWrapper.created() : super.created() {
+    binder.registerCallback(this);
+    _last = getAttribute('last') != null;
+    createShadowRoot();
+    render();
+  }
+
+  @override
+  void attached() {
+    super.attached();
+    render();
+  }
+
+  void render() {
+    shadowRoot.children = [];
+    if (_library == null || _last == null) return;
+
+    shadowRoot.children = [
+      new NavLibraryMenuElement(library.isolate, library, last: last,
+                                 queue: ObservatoryApplication.app.queue)
+        ..children = [new ContentElement()]
+    ];
+  }
+}