RFR: 8130051 Cleanup usage of reflection in jaxp

[Daniel Fuchs]

Hi,

Please find below a patch that cleans up some of the
reflection usage in jaxp.
https://bugs.openjdk.java.net/browse/JDK-8130051

http://cr.openjdk.java.net/~dfuchs/webrev_8130051/webrev.00/

This is not a deep cleanup - it is just a first pass...
There may be some opportunity to get rid of some more
obsolete code - which can be addressed by followup
bugs/RFE (such as JDK-8129892).

I also took this opportunity to remove two files which
are not used in the JDK.

jaxp/test, jdk/test/javax/xml/jaxp, and JCK test suites
(api/javax_xml api/xinclude api/xsl xml_schema) passed.

best regards,

-- daniel