Roll ANGLE from 6e909d940753 to 51603c63d1cb (1 revision)

https://chromium.googlesource.com/angle/angle.git/+log/6e909d940753..51603c63d1cb

2021-01-09 syoussefi@chromium.org Revert "Use is_apple instead of is_mac and is_ios everywhere"

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 ianelliott@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: chromium:1161513
Tbr: ianelliott@google.com
Change-Id: I838e9f10285b5569eecbc1dc3d74b5fe2a690876
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2619462Reviewed-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@{#841807}

DEPS

@@ -211,7 +211,7 @@ 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': '6e909d9407534e3b7e4eb42e49941256a14066b5',
+  'angle_revision': '51603c63d1cb9e36afaf2069fc069e542ac2f3fb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.