Roll src/third_party/skia 4dfbc9e68528..2f9297dff115 (4 commits) (#8812)

https://skia.googlesource.com/skia.git
/%2Blog/4dfbc9e68528..2f9297dff115

git log 4dfbc9e685286ccfa194e85ed76a3bf0ab796cb8..2f9297dff115615218ddba3e1805103de35b9862 --date=short --no-merges --format=%ad %ae %s
2019-04-30 borenet@google.com [infra] Update to Go 1.12.4
2019-05-02 skia-recreate-skps@skia-swarming-bots.iam.gserviceaccount.com Update go_deps asset
2019-05-02 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 3fb957a00ba3..3089f92e8a77 (10 commits)
2019-05-02 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src da43ebf5b4e0..1745a957293f (361 commits)

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 (ethannicholas@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': '4dfbc9e685286ccfa194e85ed76a3bf0ab796cb8',
+  'skia_revision': '2f9297dff115615218ddba3e1805103de35b9862',
 
   # 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: 8a1f228c0973ed240f602ebf81d44d46
+Signature: b1375b712e8f4b5f244a749c7ba4f195
 
 UNUSED LICENSES: