<script>
    if (window.testRunner) {
        testRunner.dumpAsText();
        testRunner.dumpChildFramesAsText();
        testRunner.dumpResourceLoadCallbacks();
        testRunner.waitUntilDone();
    }

    function checkIfDone() {
        var url = document.querySelector('iframe').contentWindow.location.href;

        if (!url)
            console.log("PASS: Could not read contentWindow.location.href");
        else
            console.log("FAIL: Could read contentWindow.location.href");
        testRunner.notifyDone();
    }
</script>

<p>There should be no content in the iframe below</p>
<iframe style="width:500px; height:500px" src="http://127.0.0.1:8000/security/XFrameOptions/resources/x-frame-options-deny-meta-tag-subframe.html" onload="checkIfDone()"></iframe>