On the fsfs-format7 branch:  Simplify open_and_seek_transaction() signature.

* subversion/libsvn_fs_fs/cached_data.c
  (open_and_seek_transaction): drop TXN_ID parameter as it is already part
   of the representation struct *REP.
  (open_and_seek_representation): update caller

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1454558 13f79535-47bb-0310-9956-ffa450edef68