RFR (JAXP): 8132091: Clean up JAXP code that has dependency on Java version string

[huizhe wang]

Hi,

This is a clean-up of the code in jaxp that had depended on Java version 
string. This code came from JAXP standalone that no longer exists.

jbs: https://bugs.openjdk.java.net/browse/JDK-8132091
webrev: http://cr.openjdk.java.net/~joehw/jdk9/8132091/webrev/

Thanks,
Joe