With Ben, fix some resource walk buglets:

* subversion/mod_dav_svn/update.c
  (dummy_window_handler): New function.
  (upd_apply_textdelta): If this is a resource walk, then just use
    dummy_window_handler instead of the real window_handler.
  (upd_change_xxx_prop): If this is a resource walk, then leave.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/issue-1429-dev@847790 13f79535-47bb-0310-9956-ffa450edef68