~15x speedup without needing to use SSE.
~15x speedup without needing to use SSE.

On my desktop, the bench improves from ~6ms to ~0.4ms.

BUG=skia:

Review URL: https://codereview.chromium.org/864083002

google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot