Reduced test case:

path.moveTo(               412.5,                  300);
path.lineTo( 354.331451416015625,   381.34136962890625);
path.lineTo( 444.551666259765625, 205.2757110595703125);
path.lineTo( 313.342864990234375,       287.0439453125);
path.lineTo(   354.3314208984375,   381.34136962890625);
path.lineTo(               412.5,                  300);

Yeah not likimg it so muchto me its a classic case of if its not broken dont fix it. 
But thats just what we as people cant resist

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/5926f2da752d1bff0051fda4137bb967f9e91d5f

commit 5926f2da752d1bff0051fda4137bb967f9e91d5f
Author: Stephen White <senorblanco@chromium.org>
Date: Mon Feb 13 21:18:10 2017

GrTessellator (AA): fix "Canvas Arcs" coverage artifact.

When sanitizing contours, if the first and last vertices coincide,
continue with the previous vertex, not the next vertex, since we
may otherwise exit prematurely. Also, round the last vertex before
entering the loop, just in case it coincides with the first.

Add a test case to exercise the above, and another one which exercises
the intruding-vertex workaround.

BUG= 691593 

Change-Id: Ic28a9308a21164d185edef0ee6fbc29b40742149
Reviewed-on: https://skia-review.googlesource.com/8364
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Stephen White <senorblanco@chromium.org>

[modify] https://crrev.com/5926f2da752d1bff0051fda4137bb967f9e91d5f/gm/concavepaths.cpp
[modify] https://crrev.com/5926f2da752d1bff0051fda4137bb967f9e91d5f/src/gpu/GrTessellator.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b1df829bf7a49fc52274b2651d4688a5454718ef

commit b1df829bf7a49fc52274b2651d4688a5454718ef
Author: skia-deps-roller <skia-deps-roller@chromium.org>
Date: Mon Feb 13 23:49:18 2017

Roll src/third_party/skia/ d2d6d726f..5926f2da7 (4 commits).

https://skia.googlesource.com/skia.git/+log/d2d6d726fa3e..5926f2da752d

$ git log d2d6d726f..5926f2da7 --date=short --no-merges --format='%ad %ae %s'
2017-02-13 senorblanco GrTessellator (AA): fix "Canvas Arcs" coverage artifact.
2017-02-13 reed add gm for clipRegion
2017-02-11 mtklein Enable sse2 backend for SkSplicer.
2017-02-13 herb Revert "Always make SkImageShaders in heap."

Created with:
  roll-dep src/third_party/skia
BUG= 691593 

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
TBR=bungeman@google.com

Review-Url: https://codereview.chromium.org/2691113003
Cr-Commit-Position: refs/heads/master@{#450154}

[modify] https://crrev.com/b1df829bf7a49fc52274b2651d4688a5454718ef/DEPS