handle large conic strokes better

handle large conic strokes better

A stroked conic computes the outset quad's control point by
computing the intersection of the quad's endpoints. If the
the denominator used to compute the scale factor for the
control point is small, check to see if the numerator is also
small so that the division stays bounded.

Also clean up error returns and internal function calls to
simplify the code.

Additionally, remove comic max curvature (unimplemented) and call
extrema functions instead to handle cases where the conic is degenerate
or is a line.

R=reed@google.com, fmalita@chromium.org
BUG=skia:3843
Committed: https://skia.googlesource.com/skia/+/612f70d5fa2d4bf7a393c791966bbce933407017

[caryclark, 2015-05-19 15:29:12]

The CQ bit was checked by caryclark@google.com

[commit-bot: I haz the power, 2015-05-19 15:29:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144883003/20001

[commit-bot: I haz the power, 2015-05-19 15:29:28]

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 2015-05-19 21:29 UTC

[commit-bot: I haz the power, 2015-05-19 15:33:46]

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

[commit-bot: I haz the power, 2015-05-19 15:33:47]

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, 2015-05-19 16:58:02]

lgtm

[caryclark, 2015-05-19 17:25:18]

The CQ bit was checked by caryclark@google.com

[caryclark, 2015-05-19 17:25:18]

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/1144883003/#ps40001
(title: "fix degenerate line; remove conic max curvature")

[commit-bot: I haz the power, 2015-05-19 17:25:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144883003/40001

[commit-bot: I haz the power, 2015-05-19 17:41:31]

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

[commit-bot: I haz the power, 2015-05-19 17:41:32]

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...)

[caryclark, 2015-05-19 17:58:53]

The CQ bit was checked by caryclark@google.com

[caryclark, 2015-05-19 17:58:54]

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/1144883003/#ps10004
(title: "fix dm-driven very large curve case")

[commit-bot: I haz the power, 2015-05-19 17:59:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1144883003/10004

[commit-bot: I haz the power, 2015-05-19 18:05:42]

Committed patchset #4 (id:10004) as
https://skia.googlesource.com/skia/+/612f70d5fa2d4bf7a393c791966bbce933407017