Roll Skia from 7d3f089e5811 to 6e7cfaff1817 (8 revisions)

https://skia.googlesource.com/skia.git/+log/7d3f089e5811..6e7cfaff1817

2020-11-03 johnstiles@google.com Fix bad FP codegen when sample() calls are inlined.
2020-11-03 johnstiles@google.com Poison unallocated block memory in GrBlockAllocator.
2020-11-03 herb@google.com move subrun instances and support to .cpp
2020-11-03 johnstiles@google.com Improve support for function prototypes in SkSL.
2020-11-03 bsalomon@google.com Revert changes to unbreak bots.
2020-11-03 herb@google.com cull glyphs that have far out positions
2020-11-03 bsalomon@google.com Revert "Reland "heif: Add AVIF type and AVIF sniffing""
2020-11-03 michaelludwig@google.com Avoid redundant matrix inverse for DF text ops

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 bsalomon@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: bsalomon@google.com
Change-Id: I7c99adeb53992fec6096f187e144128784021dbb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2518632
Reviewed-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@{#823774}