Roll src/third_party/skia/ 22f4a1fd4..86cedfc31 (6 commits).

https://skia.googlesource.com/skia.git/+log/22f4a1fd4859..86cedfc31588

$ git log 22f4a1fd4..86cedfc31 --date=short --no-merges --format='%ad %ae %s'
2016-12-20 robertphillips Fix iOS build
2016-12-20 brianosman Tag string bitmaps (for GMs) as sRGB
2016-12-20 robertphillips Restore getDevice_just_for_deprecated_compatibility_testing
2016-12-20 brianosman Do color space conversion in XfermodeImageFilter
2016-12-20 jvanverth Floor to scalar for SDF paths.
2016-12-20 scroggo Update libwebp to v0.5.2-rc2

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=rmistry@google.com

Review-Url: https://codereview.chromium.org/2590783004
Cr-Commit-Position: refs/heads/master@{#439853}

DEPS

@@ -40,7 +40,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': '22f4a1fd4859aa75133de37a24b3201cce5d6844',
+  'skia_revision': '86cedfc315886037a0fba6d72ba53bf47bd0b539',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.