Roll src/third_party/skia 0b2c05470bab..bcfbf6e94c22 (8 commits) (#7956)

https://skia.googlesource.com/skia.git/%2Blog/0b2c05470bab..bcfbf6e94c22

git log 0b2c05470bab8ac250d510384f3511574ca35444..bcfbf6e94c2272b0a030a8763e2abcfe4b55395c --date=short --no-merges --format=%ad %ae %s
2019-02-25 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 c63d95525cde..0546b5380780 (4 commits)
2019-02-25 bungeman@google.com Add full definition of SkStreamAsset.
2019-02-25 csmartdalton@google.com sksl: Negate dFdy when the Y axis is flipped
2019-02-25 csmartdalton@google.com Revert "Stack-allocate pipelines for GrMeshDrawOp"
2019-02-25 recipe-roller@chromium.org Roll recipe dependencies (trivial).
2019-02-25 bungeman@google.com SkTypeface::onOpenStream to return unique_ptr.
2019-02-25 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 8c1e8f1fb771..9b433073ba38 (1 commits)
2019-02-25 kjlubick@google.com [pathkit][canvaskit] roll versions

The AutoRoll server is located here: https://autoroll.skia.org/r/skia-flutter-autoroll

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

If the roll is causing failures, please contact the current sheriff (scroggo@google.com), and stop
the roller if necessary.

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': '0b2c05470bab8ac250d510384f3511574ca35444',
+  'skia_revision': 'bcfbf6e94c2272b0a030a8763e2abcfe4b55395c',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the

ci/licenses_golden/licenses_skia

-Signature: 05da1111732aec79c0ada61abc030278
+Signature: 186c1643cc6eaf037a08e71cb906d1e6
 
 UNUSED LICENSES: