Automatically generate most constructors

client/dom/templates/dom/frog/factoryprovider_HTMLAudioElement.darttemplate

Index: client/dom/templates/dom/frog/factoryprovider_HTMLAudioElement.darttemplate
diff --git a/client/dom/generated/src/interface/DOMURL.dart b/client/dom/templates/dom/frog/factoryprovider_HTMLAudioElement.darttemplate
similarity index 59%
copy from client/dom/generated/src/interface/DOMURL.dart
copy to client/dom/templates/dom/frog/factoryprovider_HTMLAudioElement.darttemplate
index 6744630cbc6a256ddc357ff222d2059d2ef38e02..c6288fe9b813cabd7150368a56707200ad8c623e 100644
--- a/client/dom/generated/src/interface/DOMURL.dart
+++ b/client/dom/templates/dom/frog/factoryprovider_HTMLAudioElement.darttemplate
@@ -2,7 +2,10 @@
 // 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.
 
-// WARNING: Do not edit - generated code.
-
-interface DOMURL {
+class $FACTORYPROVIDER {
+  factory HTMLAudioElement([String src = null]) native
+'''
+if (src == null) return new Audio();
+return new Audio(src);
+''';
 }