[8u] approval request for 8055917: jdk.nashorn.internal.codegen.CompilationPhase$N should be renamed to proper classes

[Sundararajan Athijegannathan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8055917
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-September/005233.html
jdk8u webrev: http://cr.openjdk.java.net/~sundar/8055917/8u/webrev.00/
The patch wouldn't apply cleanly as there are code differences between 
jdk9 and jdk8u nashorn repos. I did manual changes after applying the 
patch. I'm CC'ing nashorn team for further review.

Thanks,
-Sundar