Let DM run unit tests.

Let DM run unit tests.
  - refactor GYPs and a few flags
  - make GPU tests grab a thread-local GrContextFactory when needed as we do in DM for GMs
  - add a few more UI features to make DM more like tests

I believe this makes the program 'tests' obsolete.

It should be somewhat faster to run the two sets together than running the old binaries serially:
  - serial: tests 20s (3m18s CPU), dm 21s (3m01s CPU)
  - together: 27s (6m21s CPU)

Next up is to incorporate benches.  I'm only planning there on a single-pass sanity check, so that won't obsolete the program 'bench' just yet.

Tested: out/Debug/tests && out/Debug/dm && echo ok
BUG=skia:

Committed: http://code.google.com/p/skia/source/detail?r=13586

R=reed@google.com, bsalomon@google.com, mtklein@google.com, tfarina@chromium.org

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/178273002

git-svn-id: http://skia.googlecode.com/svn/trunk@13592 2bbb7eff-a529-9590-31e7-b0007b416f81