Description:
------------
Actually latest stable php i have is:
PHP 5.5.10-1~dotdeb.1 (cli) (built: Mar  6 2014 18:55:59) 
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
    with XCache v3.1.0, Copyright (c) 2005-2013, by mOo
    with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies
    with Xdebug v2.2.4, Copyright (c) 2002-2014, by Derick Rethans
    with XCache Cacher v3.1.0, Copyright (c) 2005-2013, by mOo

Error ilustrated in test script (BTW: checked in hhvm 3.1 - works as expected)

Test script:
---------------
$array = array('' => 1, 1 => 2, 3 => 4);
$ArrayObject = new ArrayObject($array);
$Iterator = $ArrayObject->getIterator();
var_dump(count($Iterator) === count($array));
//outputs false, but must be true
var_dump(iterator_to_array($Iterator));
//element '' => 1 is missing

Expected result:
----------------
count($Iterator) === count($array) must be true

Actual result:
--------------
count($Iterator) === count($array) is false