Make splash animations abort on scroll.

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

Index: sky/engine/bindings/scripts/templates/interface_cpp.template
diff --git a/sky/engine/bindings/scripts/templates/interface_cpp.template b/sky/engine/bindings/scripts/templates/interface_cpp.template
index 8d0834d4410b15fef07b9c3f7d6e1be825b9b823..839ae2716bac7c3fdabb5022a8ccdd2ed86d2730 100644
--- a/sky/engine/bindings/scripts/templates/interface_cpp.template
+++ b/sky/engine/bindings/scripts/templates/interface_cpp.template
@@ -49,7 +49,7 @@ static void namedPropertySetter(Dart_NativeArguments args)
         String name = DartConverter<String>::FromArguments(args, 1, exception);
         if (exception)
             goto fail;
-        String value = DartConverter<String>::FromArguments(args, 2, exception);
+        String value = DartConverter<String>::FromArgumentsWithNullCheck(args, 2, exception);
         if (exception)
             goto fail;
         {{named_property_setter.cpp_value}};