[8u40] Request for approval: JDK-8062401: User accessors require boxing and do not support optimistic types

[Hannes Wallnoefer]

Please approve backport of JDK-8062401 to 8u40. This is a performance 
fix, I added the noreg-perf label.

The patch applies cleanly to 8u40 after fixing path names.

Bug: https://bugs.openjdk.java.net/browse/JDK-8062401
Webrev: http://cr.openjdk.java.net/~hannesw/8062401/
Review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2014-October/003751.html
Changeset: http://hg.openjdk.java.net/jdk9/dev/nashorn/rev/6a90ece54f72

Thanks,
Hannes