Description:
------------
LimitIterator declares in its constructor that it only takes an Iterator as its inner iterator rather than just a Traversable as its parent IteratorIterator does.  That becomes a problem when, for example, an object that implements IteratorAggregate is passed into a LimitIterator.  Although IteratorAggregate will produce an Iterator via its getIterator() method, it is not itself an Iterator, just Traversable, so LimitIterator will reject it.

I'm running my code on PHP 5.2.6 but according to the documentation this is an issue in 5.3 still.  Technically this behavior is what the documentation currently reads, but I believe it is a bug that LimitIterator demands an Iterator, not just a Traversable, and therefore breaks in this case.

Test script:
---------------
class Foo implements IteratorAggregate {
  protected $array = array(1, 2, 3, 4, 5);
  public function getIterator() {
    return new ArrayIterator($this->array);
  }
}

$f = new LimitIterator(new Foo(), 0, 3);
foreach ($f as $a) {
  print $a . PHP_EOL;
}

Expected result:
----------------
1
2
3

Actual result:
--------------
Catchable fatal error: Argument 1 passed to LimitIterator::__construct() must implement interface Iterator, instance of Foo given in /blah/blah/test.php on line 10