Roll src/third_party/skia 6c2b2bb02402..df640e6d14a5 (1 commits) (flutter#13080)

https://skia.googlesource.com/skia.git/+log/6c2b2bb02402..df640e6d14a5

git log 6c2b2bb02402..df640e6d14a5 --date=short --no-merges --format='%ad %ae %s'
2019-10-11 borenet@google.com Revert "Roll recipe dependencies (trivial)."

Created with:
  gclient setdep -r src/third_party/skia@df640e6d14a5

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 kjlubick@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=kjlubick@google.com

Author: skia-flutter-autoroll

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': '6c2b2bb02402f48d06536db177c1e9612759d97b',
+  'skia_revision': 'df640e6d14a55e8331786a6dbe4492cb6bffa576',
 
   # 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: 58ed47f8a14f0b8026feab4575c85bc8
+Signature: aca5dfed087e4f09384c45ff3b7569d3
 
 UNUSED LICENSES: