Added enum checks since enums are now supported in the IDL

Source/bindings/dart/scripts/templates/methods_cpp.template

Index: Source/bindings/dart/scripts/templates/methods_cpp.template
diff --git a/Source/bindings/dart/scripts/templates/methods_cpp.template b/Source/bindings/dart/scripts/templates/methods_cpp.template
index 75c15f5576480f88b4550d10bf045f634eaaafae..fcc061456e5aefb54e6078236812c63aa4510576 100644
--- a/Source/bindings/dart/scripts/templates/methods_cpp.template
+++ b/Source/bindings/dart/scripts/templates/methods_cpp.template
@@ -247,6 +247,11 @@ if (exception)
     goto fail;
   {% endif %}
 {{argument.local_cpp_type}} {{argument.name}} = {{argument.dart_value_to_local_cpp_value}};
+{% if argument.enum_validation_expression %}
+if (!({{argument.enum_validation_expression}})) {
+  exception = Dart_NewStringFromCString("param {{argument.arg_index}} not valid");
+}
+{% endif %}
 {% endif %}
 {% endif %}{# argument.is_callback_interface #}
 if (exception)