Description:
------------
When filtering with the RegexIterator and using the ALL_MATCH mode, every element is returned, even if it does not have any matches. This functionality differs from the GET_MATCH, which does filter out empty/non-matching elements

Test script:
---------------
$it = new \ArrayIterator(array("tmp", "foo", "bar", "bazbar"));
$it = new \RegexIterator($it, "/ba(.)/", \RegexIterator::ALL_MATCHES);
print_r(iterator_to_array($it));

Expected result:
----------------
Array
(
    [0] => Array
        (
            [0] => Array
                (
                )

            [1] => Array
                (
                )

        )

    [1] => Array
        (
            [0] => Array
                (
                )

            [1] => Array
                (
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [0] => bar
                )

            [1] => Array
                (
                    [0] => r
                )

        )

    [3] => Array
        (
            [0] => Array
                (
                    [0] => baz
                    [1] => bar
                )

            [1] => Array
                (
                    [0] => z
                    [1] => r
                )

        )

)

Actual result:
--------------
Array
(
   
    [2] => Array
        (
            [0] => Array
                (
                    [0] => bar
                )

            [1] => Array
                (
                    [0] => r
                )

        )

    [3] => Array
        (
            [0] => Array
                (
                    [0] => baz
                    [1] => bar
                )

            [1] => Array
                (
                    [0] => z
                    [1] => r
                )

        )

)