Roll src/third_party/angle c12c1f571aec..df3cc205af96 (2 commits)

https://chromium.googlesource.com/angle/angle.git/+log/c12c1f571aec..df3cc205af96

git log c12c1f571aec..df3cc205af96 --date=short --first-parent --format='%ad %ae %s'
2020-04-09 angle-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/vulkan-tools/src bb32b2a70168..ae6787114fb5 (4 commits)
2020-04-09 timvp@google.com Vulkan: Support Program Pipeline Objects

Created with:
  gclient setdep -r src/third_party/angle@df3cc205af96

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 jonahr@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/+/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: jonahr@google.com
Change-Id: Ic1ba13bfc52fbac61f66bbbcd5df640f917274a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2145172Reviewed-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@{#758108}

DEPS

@@ -187,7 +187,7 @@ 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': 'c12c1f571aecb0ef14433a91f7d2ffed96349910',
+  'angle_revision': 'df3cc205af96a63e22911d366f3fd59ff14478c0',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.