added byte type support to SkSLC MSL generator

Also cleaned up converting half to float

Bug: skia:
Change-Id: I4fbb01b887b40f9e6b8cf5cdd7e03e056b29db07
Reviewed-on: https://skia-review.googlesource.com/142582
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Timothy Liang <timliang@google.com>
1 file changed