add --forceRasterPipeline to dm, (already in nanobench)

Bug: skia:
Change-Id: I0e5f7dd2aaa03340687cdfe5578c8697088cd714
Reviewed-on: https://skia-review.googlesource.com/21532
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed