Description:
------------
Serializing of LimitIterator doesn't work.


Reproduce code:
---------------
$it = new ArrayIterator(array('test' => 'test'));

$limitit = new LimitIterator($it, 0, 10);
var_dump($limitit);
var_dump($limitit->getInnerIterator());

$limititSer = serialize($limitit);
var_dump($limititSer);

$limitit = unserialize($limititSer);
var_dump($limitit);
var_dump($limitit->getInnerIterator());

Expected result:
----------------
object(LimitIterator)#2 (0) {
  /* some content */
}
object(ArrayIterator)#1 (1) {
  ["storage":"ArrayIterator":private]=>
  array(1) {
    ["test"]=>
    string(4) "test"
  }
}
string(25) "O:13:"LimitIterator":0:{...........}"
object(LimitIterator)#3 (0) {
  /* some content */
}
object(ArrayIterator)#1 (1) {
  ["storage":"ArrayIterator":private]=>
  array(1) {
    ["test"]=>
    string(4) "test"
  }
}

Actual result:
--------------
object(LimitIterator)#2 (0) {
}
object(ArrayIterator)#1 (1) {
  ["storage":"ArrayIterator":private]=>
  array(1) {
    ["test"]=>
    string(4) "test"
  }
}
string(25) "O:13:"LimitIterator":0:{}"
object(LimitIterator)#3 (0) {
}
NULL