Description:
------------
Closure use variable by ref not work with Iterator.

when use foreach on an Iterator used a Closure, the variable used by ref seems used by val.


Test script:
---------------
class OneWayIterator implements Iterator {
    protected $end = false;
    protected $getNext = null;
    protected $value = null;
    
    function __construct($next) {
        $this->getNext = $next;
    }
    
    function current() {
        return $this->value;
    }
    
    function next() {
        try {
            $this->value = call_user_func($this->getNext);
        } catch (IteratorEndException $e) {
            $this->end = true;
        }
    }
    
    function key() {
    }
    
    function valid() {
        return !$this->end;
    }
    
    function rewind() {
        try {
            $this->value = call_user_func($this->getNext);
        } catch (IteratorEndException $e) {
            $this->end = true;
        }
    }
}
class IteratorEndException extends Exception {
    
}
$i = 0;
$f = function() use (&$i) {
    if ($i >= 10) {
        throw new IteratorEndException();
    }
    return $i++;
};

foreach ($itr as $i) {
    echo "$i\n";
}


Expected result:
----------------
0
1
2
3
4
5
6
7
8
9


Actual result:
--------------
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
...