Only store width and height on SkPixelRef (part 2)

Relanding https://skia-review.googlesource.com/c/14105/
in pieces to try to diagnose problems with the Chrome
roll.

Bug: skia:6535
Change-Id: Iada034fc41ef315f7f00984d8de9d9cc2f361ad2
Reviewed-on: https://skia-review.googlesource.com/14657
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
5 files changed