Description:
------------
When using the ArrayObject::ARRAY_AS_PROPS flag with ArrayObject, empty() does not work correctly on properties defined using either array notation or object notation (and not previously declared in the object). null, false, and empty strings do not return a true value from empty().

If ARRAY_AS_PROPS is not specified, empty() works fine.

Reproduce code:
---------------
class View extends ArrayObject
{
    public function __construct(array $array = array())
    {
        parent::__construct($array, ArrayObject::ARRAY_AS_PROPS);
    }
}

$view = new View();
$view->foo = false;
$view->bar = null;
$view->baz = '';
if (empty($view['foo']) || empty($view->foo)) {
    echo "View::foo empty\n";
}
if (empty($view['bar']) || empty($view->bar)) {
    echo "View::bar empty\n";
}
if (empty($view['baz']) || empty($view->baz)) {
    echo "View::baz empty\n";
}

Expected result:
----------------
View::foo empty
View::bar empty
View::baz empty

Actual result:
--------------
No output received.