Roll src/third_party/skia ab3f867..ff84d8a (1 commits) (#7983)

https://skia.googlesource.com/skia.git/%2Blog/ab3f8674c9d2..ff84d8a900d4

git log ab3f867..ff84d8a --date=short --no-merges --format=%ad %ae %s
2019-02-26 bungeman@google.com SkTypeface::openStream to return smart pointer.

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 (scroggo@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': 'ab3f8674c9d2b28356eda74cbd35b3a8a7835752',
+  'skia_revision': 'ff84d8a900d4b9dd4d4aa7a9569425f0ac234830',
 
   # 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: b3bf5a7ca4cf5663793c3fccb721c742
+Signature: 1bea5458095c0f6e6943f64d781b6e6f
 
 UNUSED LICENSES: