Roll Skia from 4c97814f3adc to 2b8940ee5e08 (6 revisions)

https://skia.googlesource.com/skia.git/+log/4c97814f3adc..2b8940ee5e08

2020-08-05 mtklein@google.com remove SkRP-based runtime effects
2020-08-05 mtklein@google.com allow SkSpriteBlitter::setup() to fail
2020-08-05 jvanverth@google.com Switch GN defs on Mac and iOS to use frameworks, take 2.
2020-08-05 michaelludwig@google.com Specify aa type of draw to the GrClip
2020-08-05 johnstiles@google.com Update SymbolTable::takeOwnership interface to improve type safety.
2020-08-05 mtklein@google.com allow SkRP color filters to fail

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-autoroll
Please CC herb@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/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux-blink-rel;luci.chromium.try:linux-chromeos-compile-dbg;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Cq-Do-Not-Cancel-Tryjobs: true
Bug: None
Tbr: herb@google.com
Change-Id: I0d33a50ba8fe741671cf8969f717bcc28e042a6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2339767Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#795235}

DEPS

@@ -195,7 +195,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': '4c97814f3adc8af74f73451b598a6a8d2d7c4eb1',
+  'skia_revision': '2b8940ee5e0800ef20653b26e8bdce499c9556a7',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.