Description:
------------
array_walk and array_walk_recursive can alter private and protected object / class variables outside the scope of the object / class.

Reproduce code:
---------------
class Some_Class
{
    public $public = 'public string';
    protected $_protected = 'protected string';
    private $_private = 'private string';
}

function some_function(&$item, $key)
{
    $item = 'public access';
}

$Somme_Class = new Some_Class();
array_walk($Somme_Class, 'some_function');
echo '<pre>' . print_r($Somme_Class, true) . '</pre>';

$Another_Class = new Some_Class();
array_walk_recursive($Another_Class, 'some_function');
echo '<pre>' . print_r($Another_Class, true) . '</pre>';

Expected result:
----------------
Some_Class Object
(
    [public] => public access
    [_protected:protected] => protected string
    [_private:private] => protected string
)

Some_Class Object
(
    [public] => public access
    [_protected:protected] => protected string
    [_private:private] => private string
)

or an error message like : 
Fatal error: Cannot access protected property Some_Class::$_protected
or 
Warning: array_walk() expects parameter 1 to be array, object given

Actual result:
--------------
Some_Class Object
(
    [public] => public access
    [_protected:protected] => public access
    [_private:private] => public access
)

Some_Class Object
(
    [public] => public access
    [_protected:protected] => public access
    [_private:private] => public access
)