[hl] hl-check failure with abstract over Dynamic

```haxe
import haxe.xml.Fast;

class Main {
public static function main() {
var data:Wrapper = null;
new Fast(data);
}
}

abstract Wrapper(Dynamic) from T to T {}
```

```
Error:
Main.hx:6: Check failure at fun@21 @2 - Register 0(dyn) should be object
```