Roll Skia from 066f411b2ae6 to d15c52d2333e (3 revisions) (flutter#24580)

https://skia.googlesource.com/skia.git/+log/066f411b2ae6..d15c52d2333e

2021-02-23 [email protected] make GrTextBlob::addMultiMaskFormat private
2021-02-23 [email protected] Performance experiment: Disable SkSL optimization in nanobench/skpbench
2021-02-23 [email protected] Flutter does use legacy image.makeShader()

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 [email protected] 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/+doc/master/autoroll/README.md

Author: skia-flutter-autoroll

DEPS

@@ -27,7 +27,7 @@ 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': '066f411b2ae6154c5639553c3b3a98000dfa33b4',
+  'skia_revision': 'd15c52d2333e9b3f732fe2b14e38c1952298d5ec',
 
   # 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: de247b1722242e0e190418af4b1bf709
+Signature: 66d72e85dbac0f2624fe53ee1c83a79f
 
 UNUSED LICENSES: