Please review JDK-8010701 - Final part of immutable IR

[Marcus Lagergren]

http://cr.openjdk.java.net/~lagergren/8010701/webrev/

It is with great satisfaction that I can announce that Attila and I are done with the completely immutable IR. We have as a proof of concept also removed Node.CopyState altogether. There can now be copies of the same reference node in the IR and that is OK. This saves memory and ensures that we can clone code correctly (i.e. with a meaningless operation, rather than with the deep clone that was afflicted with literally dozens of bugs). 

All IR changes are now copy on write - which create new nodes. This is the responsibility of the caller.

Everything runs. 

Individual patches are at http://cr.openjdk.java.net/~lagergren/8010701/ if the webrev is too much

/M