Perhaps you could use
document.forms['frmName'].action = window.opener();
document.forms['frmName'].submit();
window.close();
This should submit your form to the "parent" page and close the newly opened page..
If you haven't opened this new window by a script/ link the user will get a security message, somthing like "The script is trying to close this page. Agree?" This is caused by the UniversalBrowserWritePrivilege variable. 🙂