<!DOCTYPE html> <script> if (window.testRunner) testRunner.dumpAsText(); </script> <div id="parent" style="width: 200px; height: 200px;"> <iframe id="iframe" seamless src="about:blank"></iframe> </div> <script> window.onload = function () { window.iframe = document.getElementById("iframe"); alert("Ready"); window.iframe.contentDocument.write("<!DOCTYPE html><html style='width: 100px; height: 100px; background-color: green'></html>"); window.iframe.contentDocument.close(); alert("PASS"); } </script>