Roll src/third_party/skia 1b9f889628e0..c6671be0ea75 (1 commits) (#8020)

https://skia.googlesource.com/skia.git/%2Blog/1b9f889628e0..c6671be0ea75

git log 1b9f889628e06943b513ff0c3fa92b697f74fe3e..c6671be0ea75880626807c4c40792b2cb1301a39 --date=short --no-merges --format=%ad %ae %s
2019-03-03 reed@google.com Revert "bring back lowp bilerp_clamp_8888"

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 (reed@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': '1b9f889628e06943b513ff0c3fa92b697f74fe3e',
+  'skia_revision': 'c6671be0ea75880626807c4c40792b2cb1301a39',
 
   # 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: 73c98299e045f328ed19b7afd55d4a9c
+Signature: 2b57e01df9555987af14385e5f1867f6
 
 UNUSED LICENSES: