Incorrect unpickling of path-dependent types

In some cases after unpickling path-dependent types become type projections. Example:

``` scala
trait Z {
  type Q
  def test: Q
}
class X(val x: Z)
class Y(x: Z) extends X(x) {
  x.test
}
```

x.test before pickling:

```
<<Y.this.x:=> Z>.test:=> Y.this.x.Q>
```

x.test after unpickling:

```
<<Y.this.x:=> Z>.test:=> Z#Q>
```
