After JDK-8003426, UseFastEmptyMethods and UseFastAccessorMethods are only used for Zero. We need to see if those can be removed. Zero uses them to specialize the entry points for empty and getter methods.

Experiments show these are still beneficial for at least bootcycle-images.

--- Linux x86_64 zero fastdebug images:

With optimization:
real 18m8.296s
real 18m9.650s
real 18m10.991s

Without optimization:
real 18m45.772s
real 18m56.266s
real 20m47.285s

--- Linux x86_64 zero release images

With optimization:
real 9m10.110s
real 9m22.675s

Without optimization:
real 9m32.046s
real 9m32.095s

--- Linux x86_64 zero release bootcycle-images

With optimization:
real 47m51.504s
real 47m35.702s

Without optimization:
real 50m19.121s
real 50m51.336s

--- SPECjvm2008

Compiler.compiler: -4.5%
Compiler.sunflow: -6.0%
MpegAudio: -4.7%
Serial: -3.3%
Sunflow: -9.6%
XmlTransform: -4.5%
XmlValidation: -4.3%