CustomElementProxy annotation

lib/interop_support.js

 // Copyright (c) 2014, 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.
 
 // Updates document.registerElement so Dart can see when Javascript custom
 // elements are created, and wrap them to provide a Dart friendly API.
 (function (doc) {
   if (window._dart_register_element_interop_support) return;
   window._dart_register_element_interop_support = true;
 
@@ skipping 17 matching lines @@
     var proto, extendsOption;
     if (options !== undefined) {
       proto = options.prototype;
     } else {
       proto = Object.create(HTMLElement.prototype);
       options = {protoptype: proto};
     }
 
     var original = proto.createdCallback;
     var newCallback = function() {
-      original.call(this);
+      if (original) original.call(this);
       var name = (this.getAttribute('is') || this.localName).toLowerCase();
       var upgrader = upgraders[name];
       if (upgrader) {
         upgrader(this);
       } else if (upgradeOldElements) {
         // Save this element in case we can upgrade it later when an upgrader is
         // registered.
         var list = pendingElements[name];
         if (!list) {
           list = pendingElements[name] = [];
@@ skipping 68 matching lines @@
           return originalGetUnknownTag(o, tag);
         }
       };
     });
   }
 
   doc._registerDartTypeUpgrader = registerDartTypeUpgrader;
   doc._onlyUpgradeNewElements = onlyUpgradeNewElements;
   doc.registerElement = registerElement;
 })(document);