Roll src/third_party/skia/ e669bdfad..276886160 (9 commits) (flutter/engine#5014)

https://skia.googlesource.com/skia.git/+log/e669bdfad6d5..276886160ba9

$ git log e669bdfad..276886160 --date=short --no-merges --format='%ad %ae %s'
2018-04-16 borenet Revert "[infra] Run recipes through Kitchen"
2018-04-16 borenet [infra] Run recipes through Kitchen
2018-04-16 angle-skia-autoroll Roll third_party/externals/angle2/ 152152618..76b2c3852 (1 commit)
2018-04-15 rmistry Increase android compile timeout
2018-04-15 reed show flatness vectors in sample
2018-04-15 update-skps Update SKP version
2018-04-14 egdaniel Revert "Delete getRenderTargetHandle call on SkSurface."
2018-04-13 liyuqian Cumulate deltas even if they're out of the clip
2018-04-14 rmistry Reland "Whitespace change"

Created with:
  roll-dep src/third_party/skia

DEPS

@@ -23,7 +23,7 @@ vars = {
   'fuchsia_git': 'https://fuchsia.googlesource.com',
   'github_git': 'https://github.com',
   'skia_git': 'https://skia.googlesource.com',
-  'skia_revision': 'e669bdfad6d5f6011e539c0631ea76e392462fa7',
+  'skia_revision': '276886160ba96748c901b7319ca8f876415269c6',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the