Only store width and height on SkPixelRef (part 1)

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

Bug: skia:6535
Change-Id: Ic321c437ecd3cb7940a48fd73fc22b192804c67a
Reviewed-on: https://skia-review.googlesource.com/14650
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
5 files changed