[8u-dev] Request for Approval: 8134609: Allow constructors with same prototoype map to share the allocator map

[Hannes Wallnoefer]

Please approve backport of 8134609 to 8u-dev.

Bug: https://bugs.openjdk.java.net/browse/JDK-8134609
Webrev: http://cr.openjdk.java.net/~hannesw/8134609/webrev.01/
Review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-September/005226.html

Changes apply cleanly to jdk8u-dev after path reshuffling.

Thanks,
Hannes