Roll ANGLE from ed87c16ad00e to 2ffff6d024c7 (6 revisions)

https://chromium.googlesource.com/angle/angle.git/+log/ed87c16ad00e..2ffff6d024c7

2020-11-17 syoussefi@chromium.org Vulkan: Support image buffers
2020-11-17 cclao@google.com Vulkan: Experimental: forcing highp to mediump in fragment shader.
2020-11-17 syoussefi@chromium.org Default deqp to Vulkan on !Apple
2020-11-17 kainino@chromium.org Add TODOs for Apple DTK skips; update bug urls
2020-11-17 m.maiya@samsung.com Vulkan: Add EXT_external_buffer support
2020-11-17 kainino@chromium.org Disable more tests for Apple DTK (macOS ARM)

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 cnorthrop@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:1132295
Tbr: cnorthrop@google.com
Test: Test: ExternalBufferTestES31.*Vulkan
Change-Id: I8c92db1567a6d8a991a714bc03203676c4d2c706
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2545703Reviewed-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@{#828588}

DEPS

@@ -209,7 +209,7 @@ 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': 'ed87c16ad00e613cd97472e7f840346be40234fd',
+  'angle_revision': '2ffff6d024c7d639ecf4258402c2d047bb09588a',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.