8067170: Enable security manager on JAXP unit tests and make some improvement
8130494: [TESTBUG] 2 jaxp test cases are failing
8160216: jaxp/test/javax/xml/jaxp/unittest/validation/Bug6457662.java should clean up better
Reviewed-by: joehw, dfuchs, amlu
Contributed-by: Frank Yuan <frank.yuan@oracle.com>