Bug fix for cull_line in SkDashPathEffect.

Bug fix for cull_line in SkDashPathEffect.

In cull_line we must also check if both points are the same. Otherwise we
fail the assert in the else "SkASSERT(dy && !dx)".

This is currently blocking the roll as it fails a webkit test.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/21402e3851454e90329bad52893f29959da086f7

[egdaniel, 2014-11-05 02:17:00]

egdaniel@google.com changed reviewers:
+ reed@google.com, robertphillips@google.com

[egdaniel, 2014-11-05 02:17:01]

A fix to Rob's recent cl

[robertphillips, 2014-11-05 12:44:44]

lgtm

[robertphillips, 2014-11-05 12:44:48]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2014-11-05 12:45:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/703783002/20001

[commit-bot: I haz the power, 2014-11-05 12:48:24]

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

[commit-bot: I haz the power, 2014-11-05 12:48:25]

Try jobs failed on following builders:
  Build-Win-VS2013-x86-Debug-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Win-VS2013-x86...)

[robertphillips, 2014-11-05 12:51:39]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2014-11-05 12:52:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/703783002/20001

[commit-bot: I haz the power, 2014-11-05 13:02:31]

Committed patchset #2 (id:20001) as 21402e3851454e90329bad52893f29959da086f7