<!DOCTYPE html>
<html>
<head>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
var sheet = document.createElement("style");
document.getElementsByTagName("head")[0].appendChild(sheet);
new MessageEvent("Message", { "data": {}, get "source"() { sheet.parentNode.removeChild(sheet); } } );
</script>
</head>
<body>
<div>Pass when no crash observed.</div>
</body>
</html>