Fixed #13068 (again) -- Corrected the admin stacked inline template to allow prepopulated fields to work (Thanks Stanislas Guerra for the report). Also fixed a regression introduced in [16953] where prepopulated fields wouldn't be recognized any more due to the additional "field-" CSS class name prefix.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17562 bcc190cf-cafb-0310-a4f2-bffc1f526a37