Roll src/third_party/skia feb720f746dc..512e38091c85 (11 commits) (#8169)

https://skia.googlesource.com/skia.git/%2Blog/feb720f746dc..512e38091c85

git log feb720f746dcecfd80e47b060d620c3ffa29a43b..512e38091c8511847334b89365d46cbb0452309a --date=short --no-merges --format=%ad %ae %s
2019-03-14 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/angle2 37b996425a0e..979f3bbe2c50 (5 commits)
2019-03-14 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-03-14 mtklein@google.com skvx: allow more implicit conversions
2019-03-14 michaelludwig@google.com Avoid unsafe casts to int in SkNx
2019-03-14 mtklein@google.com update docs for SkLumaColorFilter
2019-03-14 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-03-14 ethannicholas@google.com re-re-fixed RelaxedPrecision
2019-03-14 robertphillips@google.com Allocate the backing SkBitmap in the SerializedImageFilter fuzzer
2019-03-14 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-03-14 skia-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/externals/swiftshader eb7cf3c4b0b1..af973b67141e (2 commits)
2019-03-14 michaelludwig@google.com Reland "Update SkCanvas' experimental SkiaRenderer API"

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 (benjaminwagner@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': 'feb720f746dcecfd80e47b060d620c3ffa29a43b',
+  'skia_revision': '512e38091c8511847334b89365d46cbb0452309a',
 
   # 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: d9f6707a9eabeae331acff2af41e7b80
+Signature: 0b30f75a389dd244bf9fe53576e7b76c
 
 UNUSED LICENSES: