[8u60] approval request for 8087136: regression: apply on $EXEC fails with ClassCastException

[A. Sundararajan]

Please approve.

bug: https://bugs.openjdk.java.net/browse/JDK-8087136
jdk8u-dev webrev: 
http://cr.openjdk.java.net/~sundar/8087136/8u60/webrev.00/index.html
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-June/004738.html

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

Thanks,
-Sundar