Fixes in webui for sdk 0.6.3

lib/web_ui.dart

Index: lib/web_ui.dart
diff --git a/lib/web_ui.dart b/lib/web_ui.dart
index b7d6a37652981e0b42b4037e00f9fc3bbbea428c..40da1bc4fab5e2a1648336bf1b3199b0ed176c75 100644
--- a/lib/web_ui.dart
+++ b/lib/web_ui.dart
@@ -134,7 +134,8 @@ abstract class WebComponent implements Element {
   get isTemplate => host.isTemplate;
   get ref => host.ref;
   get content => host.content;
-  DocumentFragment createInstance() => host.createInstance();
+  DocumentFragment createInstance(model, String syntax) =>
+      host.createInstance(model, syntax);
   void bind(String name, model, String path) => host.bind(name, model, path);
   void unbind(String name) => host.unbind(name);
   void unbindAll() => host.unbindAll();