shadow-tree-listener-clearance.html

<!DOCTYPE html>
<html>
<body>
<script src="../../../resources/js-test.js"></script>
<iframe id="childFrame" src="./resources/shadow-tree-listener-clearance-frame.html"></iframe>
<script>

var child = document.getElementById("childFrame");
var firedCount = 0;

function getChildTarget()
{
    return child.contentDocument.targetInShadow;
}

function test()
{
    var toBeListened = getChildTarget();
    toBeListened.addEventListener("test", function(event) { firedCount++; });

    toBeListened.dispatchEvent(new CustomEvent("test"));
    shouldBe("firedCount", "1");

    window.child.contentDocument.open(); // This should clear event listeners
    toBeListened.dispatchEvent(new CustomEvent("test"));
    shouldBe("firedCount", "1");
    window.child.contentDocument.close();

    finishJSTest();
}

jsTestIsAsync = true;
child.addEventListener("load", test);

</script>
</body>
</html>

chromium/third_party/blink/web_tests/fast/dom/shadow/shadow-tree-listener-clearance.html