Roll src/third_party/skia 51eaa79d19b8..f3e6b90461e4 (5 commits) (flutter#7323)

https://skia.googlesource.com/skia.git/%2Blog/51eaa79d19b8..f3e6b90461e4

git log 51eaa79d19b88e1ae4ef149b1544884f92d3dae6..f3e6b90461e4c6a20cb6c79208cfcf747674b3b1 --date=short --no-merges --format=%ad %ae %s
2018-12-28 brianosman@google.com Revert &flutter#34;Wide color support in the AA linearizing convex path renderer&flutter#34;
2018-12-28 brianosman@google.com Revert &flutter#34;Wide color support in AA Convex path renderer&flutter#34;
2018-12-28 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 7f6b3674978d..cb9609fe58c2 (1 commits)
2018-12-28 mtklein@google.com move work out of GM ctor
2018-12-28 mtklein@google.com include_dirs = [ &flutter#34;tests&flutter#34; ] not needed

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 (robertphillips@google.com), and stop
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Author: skia-flutter-autoroll

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': '51eaa79d19b88e1ae4ef149b1544884f92d3dae6',
+  'skia_revision': 'f3e6b90461e4c6a20cb6c79208cfcf747674b3b1',
 
   # 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

@@ -1,4 +1,4 @@
-Signature: 83622c4ee89cf8b4e01a02ad91a4a465
+Signature: c4b0c28343555f1ba59431664fb6972e
 
 UNUSED LICENSES: