Roll src/third_party/skia 7cf4242f8adf..4dfbc9e68528 (1 commits) (#8809)

https://skia.googlesource.com/skia.git
/%2Blog/7cf4242f8adf..4dfbc9e68528

git log 7cf4242f8adf74d6e79653ed371e7ca22bc67bdb..4dfbc9e685286ccfa194e85ed76a3bf0ab796cb8 --date=short --no-merges --format=%ad %ae %s
2019-05-02 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 2e2385837e9b..20aab4e9c149 (24 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': '7cf4242f8adf74d6e79653ed371e7ca22bc67bdb',
+  'skia_revision': '4dfbc9e685286ccfa194e85ed76a3bf0ab796cb8',
 
   # 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: 813dc95c3b36540203ce59f60f5719b3
+Signature: 8a1f228c0973ed240f602ebf81d44d46
 
 UNUSED LICENSES: