SkPDF: when drawing stroked path, draw using SVG rules for zero-length segments

SkPDF: when drawing stroked path, draw using SVG rules for zero-length segments

The "zeroPath" and emptystroke GMs capture this issue.

This CL changes the following PDF GMs: emptystroke dashing4
lineclosepath dashing3 zeroPath linepath
complexclip3_complex complexclip3_simple roundrects
degeneratesegments filltypes strokerect pathfill
inverse_paths desk_chalkboard.skp

After this change, all PDF GMs look better (closer to 8888).
The dashing4, emptystroke, and zeroPath GMs still need a lot
of work to make them look right.

BUG=538726
Committed: https://skia.googlesource.com/skia/+/8b2bc252faed7c751cf9248c3833c0631f498b7d

[hal.canary, 2015-10-05 16:02:06]

halcanary@google.com changed reviewers:
+ caryclark@google.com

[hal.canary, 2015-10-05 16:02:06]

PTAL

[caryclark, 2015-10-05 16:07:55]

lgtm

[hal.canary, 2015-10-05 16:10:09]

The CQ bit was checked by halcanary@google.com

[commit-bot: I haz the power, 2015-10-05 16:10:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1374383004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1374383004/1

[commit-bot: I haz the power, 2015-10-05 16:19:04]

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

[commit-bot: I haz the power, 2015-10-05 16:19:04]

Try jobs failed on following builders:
  Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-Trybot on client.skia (JOB_FAILED,
http://build.chromium.org/p/client.skia/builders/Test-Ubuntu-GCC-GCE-CPU-AVX2...)

[reed1, 2015-10-05 16:58:33]

reed@google.com changed reviewers:
+ reed@google.com

[reed1, 2015-10-05 16:58:33]

lets add a test and/or docs before we land this

[f(malita), 2015-10-06 14:50:27]

On 2015/10/05 16:58:33, reed1 wrote:
> lets add a test and/or docs before we land this

FWIW, this should be covered by GM:zeroPath.

[hal.canary, 2015-10-06 16:34:31]

On 2015/10/05 16:58:33, reed1 wrote:
> lets add a test and/or docs before we land this

done.  Also see the amended commit message.

[hal.canary, 2015-10-06 16:35:01]

The CQ bit was checked by halcanary@google.com

[hal.canary, 2015-10-06 16:35:02]

The patchset sent to the CQ was uploaded after l-g-t-m from caryclark@google.com
Link to the patchset: https://codereview.chromium.org/1374383004/#ps60001
(title: "2015-10-06 (Tuesday) 12:31:14 EDT")

[commit-bot: I haz the power, 2015-10-06 16:35:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1374383004/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1374383004/60001

[commit-bot: I haz the power, 2015-10-06 16:41:52]

Committed patchset #4 (id:60001) as
https://skia.googlesource.com/skia/+/8b2bc252faed7c751cf9248c3833c0631f498b7d