SkSLInterpreter refactoring

A zillion little refactors:

  - small implementation simplifications all over,
    dead code removal, singleton code inlining,
    macro -> lambda, etc.

  - copy args to stack in outer run(),
    which is where we copy from stack to args.

  - scope temporaries more closely to the switch
    cases that use them rather than to all of run()

  - vertically align analogous cases,
    especially fall through

Change-Id: I7694b85724500717e6015bf7600f125c83a0d408
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/214900
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
2 files changed