[8u] approval request for 8138616: invokeFunction fails if function calls a function defined in GLOBAL_SCOPE

[Sundararajan Athijegannathan]

Please approve.

bug: https://bugs.openjdk.java.net/browse/JDK-8138616
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-October/005356.html
jdk8u-dev webrev: http://cr.openjdk.java.net/~sundar/8138616/8u/

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

Thanks,
-Sundar