RFR 8076492: Make common code from template interpreter code

[Coleen Phillimore]

Summary: Move case statement out of assembly code

Tested with JPRT for all (most) platforms - please verify AARCH64.
Also ran specjbb2005 with linux x64 - not a twitch in performance change.

open webrev at http://cr.openjdk.java.net/~coleenp/8076492/
bug link https://bugs.openjdk.java.net/browse/JDK-8076492

This code is helpful for some class redefinition improvements that I've 
been prototyping.

Thanks,
Coleen