8048869: Reduce compile time by about 5% by removing the Class.casts from the AST nodes

Removed the native casts that slow down the compiler unnecessarily. I also modified the compile-octane harness so that it can run with --verbose and --iterations flags so that you can run the compiler for an arbitrary time, gathering a mission control executing profile.

Reviewed-by: attila, jlaskey
36 files changed