Removed a redundant test in PngChunkItxt

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/imaging/trunk@1545252 13f79535-47bb-0310-9956-ffa450edef68
Private methods are implicitly final

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/imaging/trunk@1545253 13f79535-47bb-0310-9956-ffa450edef68