Roll ANGLE from d79db25910ff to f6f206018caf (2 revisions)

https://chromium.googlesource.com/angle/angle.git/+log/d79db25910ff..f6f206018caf

2020-09-19 jmadill@chromium.org Vulkan: Optimize Attribute Change Perf (4/5)
2020-09-19 timvp@google.com Remove setting a default value for use_custom_libcxx

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 jmadill@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: jmadill@google.com
Test: Test: CQTest: Test: DrawCallPerfBenchmark.Run/vulkan_null_attrib_change
Change-Id: Iaaa27ee2afc424f183120152f5df75052a7010da
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2420012Reviewed-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@{#808667}

DEPS

@@ -207,7 +207,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  'angle_revision': 'd79db25910ffd66f3d1b874b231592b8831ca4a7',
+  'angle_revision': 'f6f206018caf4008d52a311fe07466ad08bef808',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.