Roll src/third_party/skia a8ceb775c12f..d93ee53affd3 (8 commits) (#9018)

https://skia.googlesource.com/skia.git
/%2Blog/a8ceb775c12f..d93ee53affd3

git log a8ceb775c12f1516e11dd7463f0576d9fb26d524..d93ee53affd3ffaa8e3206d9358b8f9197d118bf --date=short --no-merges --format=%ad %ae %s
2019-05-20 reed@google.com Rework colorfilter bench
2019-05-20 reed@google.com simplify setColor, without needing the 4f or the colorspace
2019-05-20 bsalomon@google.com Fix async_rescale_and_read_no_bleed with --preAbandonGpuContext
2019-05-20 bsalomon@google.com Reland "Make SkSurface::asyncRescaleAndRead use kStrict constraint"
2019-05-20 robertphillips@google.com Move explicit backend object allocation API to GrContext
2019-05-17 bungeman@chromium.org Move ccpr headers for display list out of include/private.
2019-05-20 reed@google.com remove allocs for colorfilters
2019-05-17 ethannicholas@google.com support for SkSL interpreter external function calls

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 (csmartdalton@google.com), and stop
the roller if necessary.

https://dart.googlesource.com/external/github.com/flutter/engine/+/effc214730d8943c9fb37fd0bd9056839b4363be
diff --git a/commits.json b/commits.json
index 7411c9b..21c9902 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "external/github.com/flutter/engine":"20f5000bc5eef9fcf099084ed0440566392719b0",
+  "external/github.com/flutter/engine":"effc214730d8943c9fb37fd0bd9056839b4363be",
   "external/github.com/flutter/flutter":"c0125cb44a74dae6fd2cc3888546ebd7e30ce227",
   "sdk":"e9b5c9ce8b57c3073d734e916e0c1a2c0cd63751"
 }
\ No newline at end of file