Newinstance closures without "$self" parameter

This pull request removes the need to supply `$self` as first parameter inside [anonymous classes defined via closure maps](https://github.com/xp-framework/rfc/issues/279):

## Old

```php
$run= newinstance('lang.Runnable', [], [
  'run' => function($self) {
    Console::writeLine('It works - inside ', $self->getClassName());
  }
]);
```

## New 
```php
$run= newinstance('lang.Runnable', [], [
  'run' => function() {
    Console::writeLine('It works - inside ', $this->getClassName());
  }
]);
```