Roll src/third_party/skia/ a392dbaa9..e0a34e7dc (5 commits)

https://skia.googlesource.com/skia.git/+log/a392dbaa998e..e0a34e7dcddf

$ git log a392dbaa9..e0a34e7dc --date=short --no-merges --format='%ad %ae %s'
2017-03-17 bungeman Only set dw antialias mode to grayscale for A8.
2017-03-17 bsalomon Make dstreadshuffle not crash in with --preAbandonGpuContext and look better in 565
2017-03-16 herb Fix overflow bug in slow span.
2017-03-17 brianosman Add highp to specular lighting intermediate to fix iOS bots
2017-03-17 reed Revert[2] "More SkVertices implementation work""

Created with:
  roll-dep src/third_party/skia
BUG=700836


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=borenet@chromium.org

Change-Id: If977d3dd51fa89e8273373f248aa2b3ee82eceb4
Reviewed-on: https://chromium-review.googlesource.com/456491
Reviewed-by: Skia Deps Roller <skia-deps-roller@chromium.org>
Commit-Queue: Skia Deps Roller <skia-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#457816}