Fixed #9420 -- Fixed admin templates CSS.

Removed some unconditional, invalid, IE-specific notations that were
protecting IE 5 users. IE 5 is sufficiently old, we don't really need to
do that and helping that small userbase at the expense of everybody else
was a slight priority inversion.

Patch from G2P and reviwed by Wilson Miner (who made the original
changes).

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10598 bcc190cf-cafb-0310-a4f2-bffc1f526a37