[8u] approval request for 8157819: TypeError when a java.util.Comparator object is invoked as a function

[Sundararajan Athijegannathan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8157819

jdk9 review thread:
http://mail.openjdk.java.net/pipermail/nashorn-dev/2016-May/006232.html

jdk8u webrev: http://cr.openjdk.java.net/~sundar/8157819/8u/webrev.00/

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

Thanks,

-Sundar