DM: don't change byte order when unpremultiplying to compare to PNGs.

DM: don't change byte order when unpremultiplying to compare to PNGs.

We've already decoded the PNGs themselves into unpremultiplied bitmaps with native byte order.  SkColor is just not the right choice unless you get lucky.

dm -w /tmp/dm && dm -r /tmp/dm still works on Linux, and it's much closer to working on Mac:

0 tasks left, 2 failed
Failures:
  matrixconvolution_gpu
  colormatrix_gpu

BUG=skia:
R=reed@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/139943002

git-svn-id: http://skia.googlecode.com/svn/trunk@13101 2bbb7eff-a529-9590-31e7-b0007b416f81