Description:
------------
If you unserialize ArrayObject extended object, protected properties are not getting restored. In all previous php versions behavior was different, and I was unable to find any indications in docs that this has changed.

Test script:
---------------
class testObject extends ArrayObject {
    protected $test;

    public function getTest() {
        return $this->test;
    }

    public function setTest($test) {
        $this->test = $test;
    }
}

$obj = new testObject();
$obj->setTest('test');
var_dump($obj->getTest());
$obj2 = unserialize(serialize($obj));
var_dump($obj2->getTest());

Expected result:
----------------
string(4) "test"
string(4) "test"

Actual result:
--------------
string(4) "test"
NULL