Roll src/third_party/skia a3e2996b0834..947efe28de74 (6 commits) (#9853)

https://skia.googlesource.com/skia.git
/compare/a3e2996b0834..947efe28de74

git log a3e2996b08344a896884e6de050f7a2f2b80a409..947efe28de7463289f51d5faacb8b58994420ba3 --date=short --no-merges --format=%ad %ae %s
2019-07-16 bsalomon@google.com makeDeferredSurfaceContext -> makeDeferredTextureContext and makeDeferredRenderTargetContext.
2019-07-16 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-07-16 egdaniel@google.com Revert "Changes to gl BGRA renderbuffer format support."
2019-07-16 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-07-16 brianosman@google.com Generate identical shader keys for X and Y blurs when there is no domain
2019-07-16 egdaniel@google.com Changes to gl BGRA renderbuffer format support.

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 (nifong@google.com), and stop
the roller if necessary.

DEPS

@@ -26,7 +26,7 @@ vars = {
   'skia_git': 'https://skia.googlesource.com',
   # OCMock is for testing only so there is no google clone
   'ocmock_git': 'https://github.com/erikdoe/ocmock.git',
-  'skia_revision': 'a3e2996b08344a896884e6de050f7a2f2b80a409',
+  'skia_revision': '947efe28de7463289f51d5faacb8b58994420ba3',
 
   # 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: 21cac08d0c2b4d16795b7801e2d248ee
+Signature: c2faf72b77f241e6fbb4005ea89c66d8
 
 UNUSED LICENSES: