Minor tweaks per review of r31820.
Minor tweaks per review of r31820.

* subversion/libsvn_fs_base/tree.c
  (deltify_mutable): Refresh a stale comment.
  (svn_fs_base__deltify): Pass known root node kind into
    deltify_mutable() to avoid an unnecessary lookup.

Suggested by: kfogel
              brane


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@871933 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion