Roll Skia from c9b70c65436e to f4f9c3b6cc62 (3 revisions)

https://skia.googlesource.com/skia.git/+log/c9b70c65436e..f4f9c3b6cc62

2021-06-01 jcgregorio@google.com [nanobench] Report the ratio of median/min.
2021-06-01 csmartdalton@google.com Hide path tessellation shaders in private files
2021-06-01 csmartdalton@google.com Fix empty stroked rects with butt caps

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 lovisolo@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: lovisolo@google.com
Change-Id: I8624afe267e4b36d613b6021472e430f8acefaed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2930949
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Bot-Commit: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#888222}