[java,cs] fix stack overflow from closures constraints

[kLabz]

That change from #7863 doesn't seem needed (and seemed weird, even then) as tests added in the PR still pass, and was triggering a stack overflow (see forums)

I don't have a minimal repro for the stack overflow yet, will try to craft one and add as a test

class Main {
	public static function main() {}

	public static function forComparable<T : Comparable<T>>(): T->T->Void
		return (a: T, b: T) -> {}
}

typedef Comparable<T> = {
	public function compareTo(that : T) : Int;
}