move polymer.dart into dart svn

samples/third_party/todomvc/web/router_options.dart

+// Copyright (c) 2013, 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.
+
+library router_options;
+
+import 'dart:html';
+import 'package:polymer/polymer.dart';
+
+/**
+ * Given a set of child links to this page, this will add the "selected" CSS
+ * class to the link that matches window.location.hash.
+ *
+ * For example, if the current window.location.hash is "#/completed" and we
+ * have a tag like `<a href="#/completed">` it will get the class
+ * `class="selected"`, and other links will have that CSS class removed.
+ */
+@CustomTag('router-options')
+class RouterOptions extends PolymerElement {
+
+  bool get applyAuthorStyles => true;
+  var _sub;
+
+  void inserted() {
+    super.inserted();
+
+    var anchors = this.queryAll('a');
+
+    _updateHash(records) {
+      var hash = window.location.hash;
+      if (hash == '') hash = '#/';
+      for (var a in anchors) {
+        if (a.hash == hash) {
+          a.classes.add('selected');
+        } else {
+          a.classes.remove('selected');
+        }
+      }
+    }
+
+    _updateHash(null);
+    _sub = windowLocation.changes.listen(_updateHash);
+  }
+
+  void removed() {
+    _sub.cancel();
+    super.removed();
+  }
+}