LayoutTests/fast/frames/parser-append-subframe-count.html

<!DOCTYPE html>

<script>
    if (window.testRunner)
        window.testRunner.dumpAsText();

    onload = function() {
        [].forEach.call(document.querySelectorAll('a *'), function(node) {
            node.parentNode.removeChild(node);
        });
    }
</script>

<p>
    This test should not cause crashes or asserts decrementing the connected
    subframe count after the parser has moved the iframe in the adoption agency
    algorithm.
</p>

<!-- </figure> is missing to cause the adoption agency algorithm to move the iframe -->
<a><figure><iframe></iframe></a>