[8u60] approval request for 8072853: SimpleScriptContext used by NashornScriptEngine doesn't completely complies to the spec regarding exception throwing

[A. Sundararajan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8072853
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-May/033499.html
jdk8u webrev: http://cr.openjdk.java.net/~sundar/8072853/README

Backported 'as is' except for modular source code layout difference.

Thanks,
-Sundar