added 565 to 8888 conversion for gpu LCD text rendering for macOS

Bug: skia:
Change-Id: Ie24160bb098d388bf4ad69d0c2f9f8ed4beb215c
Reviewed-on: https://skia-review.googlesource.com/134508
Commit-Queue: Timothy Liang <timliang@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
3 files changed