Roll ANGLE from b4c90eee2f9f to 6ec0b23923e9 (3 revisions)

https://chromium.googlesource.com/angle/angle.git/+log/b4c90eee2f9f..6ec0b23923e9

2020-08-31 angle-autoroll@skia-public.iam.gserviceaccount.com Roll Vulkan-ValidationLayers from af56d31487bb to 0e98e894a84c (2 revisions)
2020-08-31 angle-autoroll@skia-public.iam.gserviceaccount.com Roll Chromium from 84714fcf811e to 1ca2f943e522 (3121 revisions)
2020-08-31 angle-autoroll@skia-public.iam.gserviceaccount.com Roll SPIRV-Tools from 08291a3a9e22 to f428aa39ca2b (1 revision)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/angle-chromium-autoroll
Please CC cwallez@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_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win-asan;luci.chromium.try:win_optional_gpu_tests_rel;luci.chromium.try:linux-swangle-try-x64;luci.chromium.try:win-swangle-try-x86
Bug: None
Tbr: cwallez@google.com
Change-Id: I197ebed960b18ee6a853b971befd6a0cdf0a9218
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2384857
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@{#803092}