'extends Element'

tools/dom/src/dart2js_CustomElementSupport.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 dart.dom.html;
+
+_callOnCreated(receiver) {
+  return receiver.onCreated();
+}
+
+_makeCreatedCallbackMethod() {
+  return JS('',
+      '''((function(invokeCallback) {
+             return function() {
+               return invokeCallback(this);
+             };
+          })(#))''',
+      convertDartClosureToJS(_callOnCreated, 1));
+}
+
+void _registerCustomElement(context, document, String tag, Type type) {
+  // Function follows the same pattern as the following JavaScript code for
+  // registering a custom element.
+  //
+  //    var proto = Object.create(HTMLElement.prototype, {
+  //        createdCallback: {
+  //          value: function() {
+  //            window.console.log('here');
+  //          }
+  //        }
+  //    });
+  //    document.register('x-foo', { prototype: proto });
+  //    ...
+  //    var e = document.createElement('x-foo');
+
+  var interceptorClass = findInterceptorConstructorForType(type);
+  if (interceptorClass == null) {
+    throw new ArgumentError(type);
+  }
+
+  String baseClassName = findDispatchTagForInterceptorClass(interceptorClass);
+  if (baseClassName == null) {
+    throw new ArgumentError(type);
+  }
+  if (baseClassName == 'Element') baseClassName = 'HTMLElement';
+
+  var baseConstructor = JS('=Object', '#[#]', context, baseClassName);
+  if (JS('bool', "typeof(#) != 'function'", baseConstructor)) {
+    throw new ArgumentError(type);
+  }
+
+  var properties = JS('=Object', '{}');
+
+  var jsCreatedCallback = _makeCreatedCallbackMethod();
+
+  JS('void', '#.createdCallback = #', properties,
+      JS('=Object', '{value: #}', jsCreatedCallback));
+
+  var baseProto = JS('=Object', '#.prototype', baseConstructor);
+  var proto = JS('=Object', 'Object.create(#, #)', baseProto, properties);
+
+  var interceptor = JS('=Object', '#.prototype', interceptorClass);
+
+  setNativeSubclassDispatchRecord(proto, interceptor);
+
+  JS('void', '#.register(#, #)',
+      document, tag, JS('', '{prototype: #}', proto));
+}