16-bit instructions

This should give us plenty of coding space.
If anything this seems to run faster:

Before:   21/21  MB	1	4.33ms	4.33ms	4.34ms	4.36ms	0%	▁▁▃▁▂▂▁▂▂█	8888	GM_runtime_cf_interp_1
After:    21/21  MB	1	4.17ms	4.17ms	4.17ms	4.18ms	0%	▃▂▁▅▄▃█▅▅▆	8888	GM_runtime_cf_interp_1

Change-Id: I6beb785fc0d00fb274a1f87c2fdd5ed530b96b8f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/215046
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed