views_handler_argument_date::get_default_argument does not fallback to parent::get_default_argument

I was trying to use the "Provide default argument" for a date argument, and it seemed that no matter how I would provide the argument, it would not work properly.

While debugging "views_handler_argument_date::get_default_argument()", I found out that this function would return nothing for my particular case.

I needed it to fallback to parent::get_default.. so my default argument would work...

I believe it is a bug. My patch simply removes the last else{} so there is always a fallback to parent::