compute initial winding from projected rays

Path ops formerly found the topmost unprocessed edge and determined its angle sort order to initialize the winding. This never worked correctly with cubics and was flaky with paths consisting mostly of vertical edges.

This replacement shoots axis-aligned rays through all intersecting edges to find the outermost one either horizontally or vertically. The resulting code is smaller and twice as fast.

To support this, most of the horizontal / vertical intersection code was rewritten and standardized, and old code supporting the top-directed winding was deleted.

Contours were pointed to by an SkTDArray. Instead, put them in a linked list, and designate the list head with its own class to ensure that methods that take lists of contours start at the top. This change removed a large percentage of memory allocations used by path ops.

TBR=reed@google.com
BUG=skia:3588
Committed: https://skia.googlesource.com/skia/+/624637cc8ec22c000409704d0b403ac1b81ad4b0

[caryclark, 2015-05-08 15:35:13]

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

[commit-bot: I haz the power, 2015-05-08 15:35:34]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/280001

[commit-bot: I haz the power, 2015-05-08 15:38:02]

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

[commit-bot: I haz the power, 2015-05-08 15:38:02]

Dry run: Try jobs failed on following builders:
  Build-Ubuntu-Clang-x86_64-Debug-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-Clang-x...)
  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...)
  Build-Ubuntu-GCC-Mips-Debug-Android-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-GCC-Mip...)

[caryclark, 2015-05-08 16:00:25]

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

[commit-bot: I haz the power, 2015-05-08 16:00:41]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/300001

[commit-bot: I haz the power, 2015-05-08 16:02:51]

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

[commit-bot: I haz the power, 2015-05-08 16:02:52]

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...)

[caryclark, 2015-05-08 16:23:44]

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

[commit-bot: I haz the power, 2015-05-08 16:24:02]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/320001

[commit-bot: I haz the power, 2015-05-08 16:26:26]

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

[commit-bot: I haz the power, 2015-05-08 16:26:28]

Dry run: Try jobs failed on following builders:
  Build-Ubuntu-Clang-x86_64-Debug-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-Clang-x...)

[caryclark, 2015-05-08 21:10:52]

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

[commit-bot: I haz the power, 2015-05-08 21:11:30]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/350001

[caryclark, 2015-05-08 21:13:16]

The CQ bit was unchecked by caryclark@google.com

[caryclark, 2015-05-11 13:58:48]

The CQ bit was checked by caryclark@google.com

[commit-bot: I haz the power, 2015-05-11 13:58:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/390001

[commit-bot: I haz the power, 2015-05-11 14:00:40]

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

[commit-bot: I haz the power, 2015-05-11 14:00:42]

Try jobs failed on following builders:
  Build-Ubuntu-Clang-x86_64-Debug-Trybot on client.skia.compile (JOB_FAILED,
http://build.chromium.org/p/client.skia.compile/builders/Build-Ubuntu-Clang-x...)

[caryclark, 2015-05-11 14:14:28]

The CQ bit was checked by caryclark@google.com

[commit-bot: I haz the power, 2015-05-11 14:14:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1111333002/410001

[commit-bot: I haz the power, 2015-05-11 14:21:35]

Committed patchset #22 (id:410001) as
https://skia.googlesource.com/skia/+/624637cc8ec22c000409704d0b403ac1b81ad4b0