[8u] approval request for 8137258: JSObjectLinker and BrowserJSObjectLinker should not expose internal JS objects

[Sundararajan Athijegannathan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8137258
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-September/005335.html
jdk8u webrev: http://cr.openjdk.java.net/~sundar/8137258/8u/webrev.00/

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

Thanks,
-Sundar