Roll src/third_party/angle 84780f7dc5e1..40c7a20f9bf9 (3 commits)

https://chromium.googlesource.com/angle/angle.git/+log/84780f7dc5e1..40c7a20f9bf9

git log 84780f7dc5e1..40c7a20f9bf9 --date=short --first-parent --format='%ad %ae %s'
2020-03-12 angle-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/vulkan-validation-layers/src 2ff8b6a6f4d5..be663d752e45 (8 commits)
2020-03-12 angle-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/glslang/src e2176c91b23c..9b620aa0c12d (2 commits)
2020-03-12 angle-autoroll@skia-public.iam.gserviceaccount.com Roll third_party/vulkan-loader/src 136207a63495..29adf277cb19 (1 commits)

Created with:
  gclient setdep -r src/third_party/angle@40c7a20f9bf9

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/+/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
Bug: None
Tbr: jmadill@google.com
Change-Id: I0b3c9964f9607fb42d9b78d3f269b51dd0a0b6f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2099215Reviewed-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@{#749639}

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': '84780f7dc5e191f50a5070a8ef6dc1108ee51c36',
+  'angle_revision': '40c7a20f9bf96ba9710192231c0e7ade1abea186',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.