[8u60] approval request for 8085810: Return value of Objects.requireNonNull call can be used

[A. Sundararajan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8085810
jdk8u-dev webrev: http://cr.openjdk.java.net/~sundar/8085810/8u60/webrev.00/
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-June/004671.html

This is a code clean up fix. Apart from modular source layout 
difference, the backport leaves change in one jdk9 specific file 
(ParserImpl.java). All other changes are same. CC'ing nashorn team.

Thanks,
-Sundar