Mike's radial gradient CL with better float -> int.

Mike's radial gradient CL with better float -> int.

patch from issue 1072303005 at patchset 40001 (http://crrev.com/1072303005#ps40001)

This looks quite launchable.  radial_gradient3, min of 100 samples:
  N5:  985µs -> 946µs
  MBP: 395µs -> 279µs

On my MBP, most of the meat looks like it's now in reading the cache and writing to dst one color at a time.  Is that something we could do in float math rather than with a lookup table?

BUG=skia:

CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Mac10.8-Clang-Arm7-Debug-Android-Trybot,Build-Ubuntu-GCC-Arm7-Release-Android_NoNeon-Trybot

Committed: https://skia.googlesource.com/skia/+/abf6c5cf95e921fae59efb487480e5b5081cf0ec

Committed: https://skia.googlesource.com/skia/+/1113da72eced20480491bb87ade0ffcff4eb8ea7

[mtklein, 2015-04-25 15:17:46]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-25 15:17:56]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/60001

[mtklein, 2015-04-25 15:28:06]

The CQ bit was unchecked by mtklein@google.com

[mtklein, 2015-04-25 18:59:49]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-25 18:59:58]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/80001

[commit-bot: I haz the power, 2015-04-25 19:01:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-25 19:01:28]

Dry run: Try jobs failed on following builders:
  Build-Ubuntu-GCC-Arm7-Debug-Android-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-GCC-Arm...)

[mtklein, 2015-04-25 19:06:31]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-25 19:06:36]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/100001

[mtklein, 2015-04-25 19:10:13]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-25 19:10:17]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/120001

[mtklein, 2015-04-25 19:19:43]

The CQ bit was unchecked by mtklein@google.com

[mtklein, 2015-04-25 19:19:43]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-04-25 19:19:44]

The CQ bit was unchecked by mtklein@google.com

[mtklein, 2015-04-25 19:19:52]

The CQ bit was checked by mtklein@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-04-25 19:20:01]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/120001

[commit-bot: I haz the power, 2015-04-25 19:46:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-25 19:46:10]

Dry run: This issue passed the CQ dry run.

[mtklein_C, 2015-04-25 19:57:19]

mtklein@chromium.org changed reviewers:
+ reed@google.com, robertphillips@google.com
- mtklein@google.com

[mtklein_C, 2015-04-25 19:57:20]

I'm open to landing parts first, splitting, patching this back on the original,
etc.

[reed1, 2015-04-27 17:36:45]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-04-27 17:37:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/120001

[commit-bot: I haz the power, 2015-04-27 17:37:03]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-04-27 23:37 UTC

[reed1, 2015-04-27 17:50:02]

lgtm

[commit-bot: I haz the power, 2015-04-27 18:14:01]

Committed patchset #7 (id:120001) as
https://skia.googlesource.com/skia/+/abf6c5cf95e921fae59efb487480e5b5081cf0ec

[mtklein, 2015-04-27 18:20:49]

A revert of this CL (patchset #7 id:120001) has been created in
https://codereview.chromium.org/1109883003/ by mtklein@google.com.

The reason for reverting is: compile failures..

[mtklein, 2015-04-27 18:55:38]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-04-27 18:55:38]

The patchset sent to the CQ was uploaded after l-g-t-m from reed@google.com
Link to the patchset: https://codereview.chromium.org/1109643002/#ps140001
(title: "build fixes")

[commit-bot: I haz the power, 2015-04-27 18:55:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/140001

[mtklein, 2015-04-27 19:07:43]

The CQ bit was unchecked by mtklein@google.com

[mtklein, 2015-04-27 19:07:43]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-04-27 19:07:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109643002/140001

[commit-bot: I haz the power, 2015-04-27 19:08:05]

Committed patchset #8 (id:140001) as
https://skia.googlesource.com/skia/+/1113da72eced20480491bb87ade0ffcff4eb8ea7