RFR (JAXP) 8150256: removing xerces-related dead code

[huizhe wang]

Hi,

Please review removing three unused classes from the jaxp repo.
JBS: https://bugs.openjdk.java.net/browse/JDK-8150256
Webrevs: http://cr.openjdk.java.net/~joehw/jdk9/8150256/webrev/
Tests: passed

Refer to the jaxp change history [1], the following changes in particular:

- - protected XPointerFramework fXPointerFramework = null; - protected 
XPointerSchema [] fXPointerSchema; -

The references to these classes were removed during the early JDK 6 
development.


[1] 
https://java.net/projects/jaxp-sources/sources/svn/diff/trunk/xml-xerces/java/src/com/sun/org/apache/xerces/internal/xinclude/XIncludeHandler.java?rev1=509&rev2=510

Thanks,
Joe