Roll Skia from a8b16365f92a to a5a97b4858fb (8 revisions)

https://skia.googlesource.com/skia.git/+log/a8b16365f92a..a5a97b4858fb

2020-08-18 johnstiles@google.com Replace various C-style casts in SkSLCompiler with as<T>.
2020-08-18 johnstiles@google.com Mark helper functions as static to prevent external linkage.
2020-08-18 johnstiles@google.com Add as<StatementSubclass> to downcast Statements more safely.
2020-08-18 bungeman@google.com Fix SkBitmap::allocPixels logging
2020-08-18 scroggo@google.com Switch Skia's libjpeg-turbo used for testing to Chromium version
2020-08-18 johnstiles@google.com Add as<ExpressionSubclass>() to downcast Expressions more safely.
2020-08-18 robertphillips@google.com Enhance assert to dump more information
2020-08-18 johnstiles@google.com Fix constness of ExternalValue* inside ExternalValueReference.

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 stani@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: chromium:1116848,chromium:922430
Tbr: stani@google.com
Change-Id: I3fa286b9f5e4df2ce4c1ef3eaa582ebad1208659
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363311Reviewed-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@{#799226}

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': 'a8b16365f92a69687fc65ecd27607cffea7db487',
+  'skia_revision': 'a5a97b4858fb1197c554596d3f37aca89e0dd172',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.