[8u60] approval request for 8074410: Startup time: Port shell.js to Java

[A. Sundararajan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8074410
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-March/004387.html
jdk8u-dev webrev: http://cr.openjdk.java.net/~sundar/8074410/8u60/

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

Thanks,
-Sundar