Fix #9346: Shortcut type aliases in refinements

[odersky]

No description provided.

[odersky]

@smarter Can you check whether this fixes the Akka stream issue?

[odersky]

I considered dropping recoverable_& in turn. But it might still be useful for the examples that needed it previously
if you replace refinements

   type A = T

with

   type A >: T <: T

[smarter]

Can you check whether this fixes the Akka stream issue?

Yes, looks like that did the trick! (there are still compilation errors in akka-stream but they seem to be unrelated)