Override is not resolved correctly for classes with generic parents that are narrowed down

[Schahen]

This is a strikingly simple example of something that is broken:

interface Base<T> {
  ping(o: T);
}

declare class App implements Base<number> {
  ping(o: number);
}

will be translated to:

external interface Base<T> {
    fun ping(o: T)
}

external open class App : Base<Number> {
    open fun ping(o: Number)
}

while App::ping actually should have override