Please review JDK-8048869

[Marcus Lagergren]

Please review http://cr.openjdk.java.net/~lagergren/8048869/webrev/ - sped up compile time about 5% all over the line from removing native casts from the IR nodes. Turned compile-octane into a more generic benchmark so that it can run an arbitrary number of compiles in the same process, to create a compile time profile for Nashorn.

https://bugs.openjdk.java.net/browse/JDK-8048869

/M