Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54242
Fix NPE in tagPlugins:ForEach when iteration is null. JSTL spec says it should be treated like an empty iteration. Patch provided by Sheldon Shao.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1427851 13f79535-47bb-0310-9956-ffa450edef68