Roll Skia from 20fad3206488 to a07076b6a8f9 (6 revisions)

https://skia.googlesource.com/skia.git/+log/20fad3206488..a07076b6a8f9

2020-12-23 brianosman@google.com Fix GN issue with incorrect task outputs
2020-12-23 brianosman@google.com Make all fragmentProcessors implicitly nullable in SkSL
2020-12-23 brianosman@google.com Fix skslc compilation on Windows
2020-12-23 csmartdalton@google.com Clean up GrStrokeIndirectOp #ifs for using SIMD
2020-12-23 bungeman@google.com Remove MakeDescriptorForPaths.
2020-12-23 johnstiles@google.com Fix fuzzer-discovered crash with negated swizzles.

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 bungeman@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: bungeman@google.com
Change-Id: I875de9c7a8da81fd297799c6ac26e5f11591ccfc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2602503Reviewed-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@{#839199}

DEPS

@@ -199,7 +199,7 @@ 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': '20fad3206488f7fd571010789f1ac730e6817ea0',
+  'skia_revision': 'a07076b6a8f9d78cd62a8e13a228f6c94a4a70bd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.