Infinite pickling

```scala
object Test {
  abstract class Foo { def inner: Int }

  def foo = {
    val x = 5
    if (System.currentTimeMillis > 0) { // random predicate
      class Bar extends Foo {
        def inner = x
      }

      val f = new Bar
      f.inner
    }
    else 0
  }
}
```

compiled with `-Ytest-pickler`, this compiles forever (`where forever = (>) 5`)