Dispatch with conversion hooks

lib/dom/templates/html/dart2js/html_dart2js.darttemplate

 // Copyright (c) 2012, 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.
 
 // DO NOT EDIT
 // Auto-generated dart:html library.
 
 #library('dart:html');
 
 #import('dart:isolate');
 #import('dart:json');
 
 $!GENERATED_DART_FILES
 
 #source('../../dom/src/EventListener.dart');
 #source('../../dom/src/KeyLocation.dart');
 #source('../../dom/src/KeyName.dart');
 #source('../../dom/src/ReadyState.dart');
 #source('../../dom/src/Timer.dart');
 #source('../../dom/src/_Collections.dart');
 #source('../../dom/src/_HttpRequestUtils.dart');
 #source('../../html/src/Isolates.dart');
 #source('../../html/src/Measurement.dart');
 #source('../../html/src/Serialization.dart');
 #source('../../html/src/shared_FactoryProviders.dart');
+#source('../../html/src/dart2js_Conversions.dart');
 #source('../../html/src/dart2js_DOMImplementation.dart');
 #source('../../html/src/dart2js_FactoryProviders.dart');
 #source('../../html/src/dart2js_IDBKeyRangeFactoryProvider.dart');
 #source('../../html/src/dart2js_LocationWrapper.dart');
 #source('../../dom/src/dart2js_TypedArrayFactoryProvider.dart');
 #source('../../html/src/_Testing.dart');
 #source('../../html/src/Device.dart');
 #source('../../dom/src/_ListIterators.dart');
 #source('../../dom/src/_Lists.dart');
 
 
 Window get window() native "return window;";
 _WindowImpl get _window() native "return window;";
 
 Document get document() native "return document;";
 
 _DocumentImpl get _document() native "return document;";
 
 Element query(String selector) => _document.query(selector);
 ElementList queryAll(String selector) => _document.queryAll(selector);
 
+/// Marker for defaulted arguments.
+class _Default {
+  const _Default();
+}
+
+final _default = const _Default();
+
 // Workaround for tags like <cite> that lack their own Element subclass --
 // Dart issue 1990.
 class _HTMLElementImpl extends _ElementImpl native "*HTMLElement" {
 }
 
 // Support for Send/ReceivePortSync.
 int _getNewIsolateId() native @'''
   if (!window.$dart$isolate$counter) {
     window.$dart$isolate$counter = 1;
   }
   return window.$dart$isolate$counter++;
 ''';
 
 // Fast path to invoke JS send port.
 _callPortSync(int id, message) {
   return JS('var', @'ReceivePortSync.dispatchCall(#, #)', id, message);
 }
 
 // TODO(vsm): Plumb this properly.
 spawnDomFunction(f) => spawnFunction(f);