Accessing frameElement from iframe (javascript): problem in Opera

Hi,

I have the following situation. 2 sites, say aaa.site.com and bbb.site.com. Both are accessible via https. https://aaa.site.com/1.htm contains iframe that references https://bbb.site.com/2.htm. Both have set document.domain property to 'site.com'. So they can access each other successfully. But the problem comes when https://bbb.site.com/2.htm requires authentication (basic HTTP authentication). In this case when user authenticates, javascript code from iframe can't access its parent any more. Errors console says something about accessing the protected property (when trying to access window.frameElement).
But the same thing works fine in IE8 and FF. In Opera 10 and 9.64, it doesn't.
Is there a way to make it work it Opera?
I understand this may relate to some security considerations. One page is authenticated, while another is not. But is there any way to increase the trust, since I control both pages, to allow them communicate is such situation?

Regards,
Evgeny