Crash set interface

The following example crash the VM:

```haxe

interface I {
public var __next(default, set) : I;
}

class Main implements I {

public var bits = 0;
public var __next(default, set) : I;

function set___next(v:I) {
return __next = v;
}

function new() {
}

static function foo( m : I ) {
m.__next = m;
}

static function main() {
var o = new Main();
foo(o);
o.__next.__next = o;
}

}
```