Rename Sky's custom2 to custom

sky/engine/bindings/scripts/templates/attributes_cpp.template

Index: sky/engine/bindings/scripts/templates/attributes_cpp.template
diff --git a/sky/engine/bindings/scripts/templates/attributes_cpp.template b/sky/engine/bindings/scripts/templates/attributes_cpp.template
index 6df30964262bb21d68c867264f3a1527609269d3..febec81c7377d66c2be487657480e78cd4134b73 100644
--- a/sky/engine/bindings/scripts/templates/attributes_cpp.template
+++ b/sky/engine/bindings/scripts/templates/attributes_cpp.template
@@ -83,7 +83,7 @@ static void {{static_attribute_name(attribute, 'Setter')}}(Dart_NativeArguments
     {
         {{cpp_class}}* receiver = GetReceiver<{{cpp_class}}>(args);
 {% if attribute.is_custom_element_callbacks %}
-        NewCustomElementCallbackScope deliveryScope;
+        CustomElementCallbackScope deliveryScope;
 {% endif %}
 {% set attribute_name = attribute.name if not attribute.put_forwards else 'value' %}