Roll src/third_party/skia 296743a86281..3787f51c65c3 (4 commits) (#12512)

https://skia.googlesource.com/skia.git/+log/296743a86281..3787f51c65c3

git log 296743a86281..3787f51c65c3 --date=short --no-merges --format='%ad %ae %s'
2019-09-27 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 f703443b1f67..7f506bde16f1 (9 commits)
2019-09-27 skia-recreate-skps@skia-swarming-bots.iam.gserviceaccount.com Update Go deps
2019-09-27 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader 30d3c8afe19c..6b4b8141e11d (2 commits)
2019-09-27 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src fbc0a229ff3c..996b39934b3a (495 commits)

Created with:
  gclient setdep -r src/third_party/skia@3787f51c65c3

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC bungeman@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

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

Bug: None
TBR=bungeman@google.com

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': '296743a86281b32f354016859ff70b16a9fc6e1d',
+  'skia_revision': '3787f51c65c33eda4a5f81e16b5e7e2d01f93943',
 
   # 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: 2b55e5e8794d9e040f6dba1975203e61
+Signature: 7ead2b606ba7ffb56482095ea39b87c4
 
 UNUSED LICENSES: