Fixed #9074: Added overflow: hidden to the submit-row div to clear the floated...

Fixed #9074: Added overflow: hidden to the submit-row div to clear the floated contents and avoid collapsing when the Save button is all that's there.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@9039 bcc190cf-cafb-0310-a4f2-bffc1f526a37