Scaladoc: `this.type` in type bounds is incorrectly rendered as enclosing class/trait

The following code:

```scala
class X:
  def foo[T <: this.type](): Unit = ???
```

when rendered in Scaladoc results in

```scala
def foo[T <: X](): Unit
```

## Expectation

It should be rendered as:
```scala
def foo[T <: this.type](): Unit
```