ReplicationValve is instance of ClusterValve.
Rather than get cluster instance from container on every request, use instance variable.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1482682 13f79535-47bb-0310-9956-ffa450edef68
Reduce nest.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1482683 13f79535-47bb-0310-9956-ffa450edef68