RFR 8044517: Run & debug single Nashorn test

[A. Sundararajan]

Please review

Bug: https://bugs.openjdk.java.net/browse/JDK-8044517
Webrev: http://cr.openjdk.java.net/~sundar/8044517/

This fix is contributed byJaroslav Tulach (CC'ed). I've made few 
cosmetic changes in build.xml (on the patch attached to the bug report).

Thanks,
-Sundar