Switch to lookup declaration by tag name. This fixes issue 14274.

pkg/polymer/lib/src/declaration.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;
 
 /**
  * **Warning**: this class is experiental and subject to change.
  *
  * The implementation for the `polymer-element` element.
@@ skipping 138 matching lines @@
     }
     return false;
   }
 
   void register(String name, String extendee) {
     // build prototype combining extendee, Polymer base, and named api
     buildType(name, extendee);
 
     // back reference declaration element
     // TODO(sjmiles): replace `element` with `elementElement` or `declaration`
-    _declarations[_type] = this;
+    _declarations[name] = this;
 
     // more declarative features
     desugar();
 
     // TODO(sorvell): install a helper method this.resolvePath to aid in
     // setting resource paths. e.g.
     // this.$.image.src = this.resolvePath('images/foo.png')
     // Potentially remove when spec bug is addressed.
     // https://www.w3.org/Bugs/Public/show_bug.cgi?id=21407
     // TODO(jmesserly): resolvePath not ported, see first comment in this class.
@@ skipping 15 matching lines @@
    *
    * *Note*: unlike the JavaScript version, we do not have to metaprogram the
    * prototype, which simplifies this method.
    */
   void buildType(String name, String extendee) {
     // get our custom type
     _type = _getRegisteredType(name);
 
     // get basal prototype
     _supertype = _getRegisteredType(extendee);
-    if (supertype != null) _super = _getDeclaration(supertype);
+    if (_supertype != null) _super = _getDeclaration(extendee);
 
     var cls = reflectClass(_type);
 
     // transcribe `attributes` declarations onto own prototype's `publish`
     publishAttributes(cls, _super);
 
     publishProperties(type);
 
     inferObservers(cls);
 
@@ skipping 308 matching lines @@
 
 void _notifyType(String name) {
   var waiting = _waitType.remove(name);
   if (waiting != null) waiting.registerWhenReady();
 }
 
 /// elements waiting for super, by name
 final Map _waitSuper = new Map<String, List<PolymerDeclaration>>();
 
 void _notifySuper(String name) {
-  _registered.add(name);

[Siggi Cherem (dart-lang), 2013/10/24 02:25:08]

(IIUC _notifySuper is called after the call to register.)

   var waiting = _waitSuper.remove(name);
   if (waiting != null) {
     for (var w in waiting) {
       w.registerWhenReady();
     }
   }
 }
 
-/// track document.register'ed tag names
-final Set _registered = new Set<String>();
+/// track document.register'ed tag names and their declarations
+final Map _declarations = new Map<String, PolymerDeclaration>();
 
-bool _isRegistered(name) => _registered.contains(name);
-
-final Map _declarations = new Map<Type, PolymerDeclaration>();
-
-PolymerDeclaration _getDeclaration(Type type) => _declarations[type];
+bool _isRegistered(String name) => _declarations.containsKey(name);
+PolymerDeclaration _getDeclaration(String name) => _declarations[name];
 
 final _objectType = reflectClass(Object);
 
 Map _getProperties(ClassMirror cls, Map props, bool matches(metadata)) {
   for (var field in cls.variables.values) {
     if (field.isFinal || field.isStatic || field.isPrivate) continue;
 
     for (var meta in field.metadata) {
       if (matches(meta.reflectee)) {
         if (props == null) props = {};
@@ skipping 114 matching lines @@
   return map;
 }();
 
 // Dart note: we need this function because we have additional renames JS does
 // not have. The JS renames are simply case differences, whereas we have ones
 // like doubleclick -> dblclick and stripping the webkit prefix.
 String _eventNameFromType(String eventType) {
   final result = _reverseEventTranslations[eventType];
   return result != null ? result : eventType;
 }