Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56339
Avoid an infinite loop if an application calls session.invalidate() from the session destroyed event for that session.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1584919 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56343
Avoid NPE if WebSocket API JAR from RI is used.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1584924 13f79535-47bb-0310-9956-ffa450edef68