:stopdoc: directive produces Object reference

The :stopdoc: directive produces a reference to Object as a class/module when used like this:

``` ruby
# :stopdoc:
class Example
  def method_name
  end
end
```

I generated the RDoc with:

```
rdoc example.rb
```

Incidentally, no reference to Object is generated unless the method is defined.  This is ok:

``` ruby
# :stopdoc:
class Example
end
```

Using RDoc 3.8.
