LayoutTests/http/tests/security/resources/cross-frame-iframe-for-enumeration-test.html

<script>
    window.customWindowProperty = 1;
    window.history.customHistoryProperty = 1;
    window.location.customLocationProperty = 1;

    window.onload = function()
    {
        if (window.testRunner)
            testRunner.globalFlag = true;
    }
</script>