<!DOCTYPE html>

<script>
function createNodeIterator() {
    function filter() {
        nodeIterator.dummyFilterCalled = true;
        return true;
    }
    const nodeIterator = parent.document.createNodeIterator(parent.document.body, NodeFilter.SHOW_ELEMENT, filter);
    nodeIterator.dummyFilterCalled = false;
    return nodeIterator;
}
</script>
