Good point. Thanks.

I took another look at the custom runner code that caused me to request that `IgnoredClassRunner` implement `Filterable`, and I think the problem that caused me to make this feature request was due to a design problem with our custom runner and filter. The current`ParentRunner` code does the right thing for `IgnoredClassRunner`

I think we should leave `IgnoredRunner` as-is until someone has a real use case that breaks unless it is `Filterable`