F-bounded polymorphism on objects

```scala
trait X[T <: X[T]] { self: T => }
object Y extends X[Y.type]
```


This does not compile.

Related discussions:
StackOverflow thread: http://stackoverflow.com/questions/32203867/scala-f-bounded-polymorphism-on-object
@retronym also has a WIP branch to deal with this: 
https://github.com/scala/scala/commit/ca4c5020d3d2e8e843a44279cbcf9585931cb26f