fix type annotation of $

pkg/polymer/lib/src/instance.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.
 
 part of polymer;
 
 /// Use this annotation to publish a field as an attribute.
 ///
 /// You can also use [PublishedProperty] to provide additional information,
 /// such as automatically syncing the property back to the attribute.
@@ skipping 194 matching lines @@
 
   /// Map of items in the shadow root(s) by their [Element.id].
   // TODO(jmesserly): various issues:
   // * wrap in UnmodifiableMapView?
   // * should we have an object that implements noSuchMethod?
   // * should the map have a key order (e.g. LinkedHash or SplayTree)?
   // * should this be a live list? Polymer doesn't, maybe due to JS limitations?
   // Note: this is observable to support $['someId'] being used in templates.
   // The template is stamped before $ is populated, so we need observation if
   // we want it to be usable in bindings.
-  @reflectable final Map<String, Element> $ =
-      new ObservableMap<String, Element>();
+  final Map<String, dynamic> $ = new ObservableMap<String, dynamic>();
 
   /// Use to override the default syntax for polymer-elements.
   /// By default this will be null, which causes [instanceTemplate] to use
   /// the template's bindingDelegate or the [element.syntax], in that order.
   PolymerExpressions get syntax => null;
 
   bool get _elementPrepared => _element != null;
 
   /// Retrieves the custom element name. It should be used instead
   /// of localName, see: https://github.com/Polymer/polymer-dev/issues/26
@@ skipping 891 matching lines @@
 
 final Logger _observeLog = new Logger('polymer.observe');
 final Logger _eventsLog = new Logger('polymer.events');
 final Logger _unbindLog = new Logger('polymer.unbind');
 final Logger _bindLog = new Logger('polymer.bind');
 
 final Expando _eventHandledTable = new Expando<Set<Node>>();
 
 final JsObject _PolymerGestures = js.context['PolymerGestures'];