Roll src/third_party/skia 4277f01..808f021 (7 commits) (flutter#15879)

https://skia.googlesource.com/skia.git/+log/4277f0173657..808f021b51df

git log 4277f01..808f021 --date=short --first-parent --format='%ad %ae %s'
2020-01-21 brianosman@google.com Improve error handling in SkSL ByteCode
2020-01-21 brianosman@google.com Tweak pointlight3d sample to work in Raster backend
2020-01-21 jlavrova@google.com Calculating drawing area for a line with shadows
2020-01-21 benjaminwagner@google.com Revert "Reland "Pass in a SkColorType into SkImage_Gpu ctor.""
2020-01-21 reed@google.com remove the last vestiges of SkMScalar
2020-01-21 reed@google.com IWYU -- colorspace no longer includes matrix44
2020-01-21 egdaniel@google.com Pass swizzle into createProxy instead of inferring from GrPixelConfig.

Created with:
  gclient setdep -r src/third_party/skia@808f021b51df

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 benjaminwagner@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: benjaminwagner@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': '4277f01736574293d6e858341b6bbebe7b8b7978',
+  'skia_revision': '808f021b51df9ad139ad328ccf5b4630000ac5b3',
 
   # 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: dc0ff6b70217a45f0c3b5d02b4443a88
+Signature: 5385ecf4ab4b06d7b9e70d4ed767a176
 
 UNUSED LICENSES: