Roll src/third_party/skia/ 18c4943e9..ce8ea4c55 (7 commits).

https://chromium.googlesource.com/skia.git/+log/18c4943e90db..ce8ea4c55b6e

$ git log 18c4943e9..ce8ea4c55 --date=short --no-merges --format='%ad %ae %s'
2016-05-31 jcgregorio skiaserve: Add /quitquitquit handler. Will be used in the hosted debugger.
2016-05-31 robertphillips Make use of new SkLights class
2016-05-31 scroggo Fix build error
2016-05-31 mboc SkTypeface::MakeFromName to take SkFontStyle.
2016-05-31 halcanary SkXPS: clean up SkConstexprMath
2016-05-31 halcanary SkEncodedInfo: simplify
2016-05-31 bsalomon Fix bug where SkPath will convert an arc to an oval and change the starting point.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=herb@google.com

Review-Url: https://codereview.chromium.org/2026893002
Cr-Commit-Position: refs/heads/master@{#396960}

DEPS

@@ -39,7 +39,7 @@ 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': '18c4943e90db5a63ea051ac3e508c75d6613aa46',
+  'skia_revision': 'ce8ea4c55b6ecaf7132edce46b1c1ed38d7437fd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.