[polymer] interop with polymer-element and polymer.js

samples/third_party/todomvc/web/lib-elements/polymer_selection.dart

-// Copyright 2013 The Polymer Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-library todomvc.web.lib_elements.polymer_selection;
-
-import 'dart:html';
-import 'package:polymer/polymer.dart';
-
-@CustomTag('polymer-selection')
-class PolymerSelection extends PolymerElement {
-  @published bool multi = false;
-  @observable final selection = new ObservableList();
-
-  factory PolymerSelection() => new Element.tag('polymer-selection');
-  PolymerSelection.created() : super.created();
-
-  void ready() {
-    clear();
-  }
-
-  void clear() {
-    selection.clear();
-  }
-
-  getSelection() {
-    if (multi) return selection;
-    if (selection.isNotEmpty) return selection[0];
-    return null;
-  }
-
-  bool isSelected(item) => selection.contains(item);
-
-  void setItemSelected(item, bool isSelected) {
-    if (item != null) {
-      if (isSelected) {
-        selection.add(item);
-      } else {
-        selection.remove(item);
-      }
-      // TODO(sjmiles): consider replacing with summary
-      // notifications (asynchronous job)
-      asyncFire("polymer-select", detail:
-          new PolymerSelectEventDetail(isSelected, item));
-    }
-  }
-
-  select(item) {
-    if (multi) {
-      toggle(item);
-    } else if (getSelection() != item) {
-      setItemSelected(getSelection(), false);
-      setItemSelected(item, true);
-    }
-  }
-
-  toggle(item) {
-    setItemSelected(item, !isSelected(item));
-  }
-}
-
-class PolymerSelectEventDetail {
-  final bool isSelected;
-  final item;
-
-  PolymerSelectEventDetail(this.isSelected, this.item);
-}