doing minor refactoring to XSD 1.1 XSDHandler component, to reduce complexity of code. currently haven't done this on XSD 1.0 code base.

git-svn-id: https://svn.apache.org/repos/asf/xerces/java/branches/xml-schema-1.1-dev@1564227 13f79535-47bb-0310-9956-ffa450edef68