palemoon-dev/platform/dom/xul/test/window_bug757137.xul

<?xml version="1.0"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        xmlns:html="http://www.w3.org/1999/xhtml">
  <html:iframe id="f" mozbrowser="true"
               src="data:text/html;charset=utf-8,%3C!DOCTYPE html>Hi" />
</window>