[1.1.X] Fixed #12503 - form examples don't validate according to w3c

  
Thanks to skyl for the report.

Backport of r12086 from trunk


git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.1.X@12087 bcc190cf-cafb-0310-a4f2-bffc1f526a37