Its not a Chrome/WebKit issue. Infact its a Firefox issue.
Try the following, Chrome will load the iframe
<html>
<head>
<title>Iframe Test</title>
</head>
<body>
<iframe src="http://groups.google.com/"></iframe>
</body>
</html>
What is happening is, when you requrest for the webpage groups.google.com/group/websync
google web server is setting HTTP header
X-Frame-Options: SAMEORIGIN
When X-Frame-Options: is set to SAMEORIGIN, the browser suppose to only allow
the content to be framed by pages within the same origin domain, i.e unless your
page is coming from google.com, browser is not suppose to let you frame the
content of http://groups.google.com/group/websync.
WebKit is doing a better job.