newforms-admin: Moved first_form_field_id calculation from render_change_form() to AdminForm()

git-svn-id: http://code.djangoproject.com/svn/django/branches/newforms-admin@4375 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/admin/options.py

@@ -76,6 +76,10 @@ class AdminForm(object):
         for fieldset in self.fieldsets:
             yield BoundFieldset(self.form, fieldset)
 
+    def first_field(self):
+        for bf in self.form:
+            return bf
+
 class Fieldset(object):
     def __init__(self, name=None, fields=(), classes=(), description=None):
         self.name, self.fields = name, fields