Roll src/third_party/angle 5a42da564fbe..6b60dfd80e3d (3 commits)

https://chromium.googlesource.com/angle/angle.git/+log/5a42da564fbe..6b60dfd80e3d

git log 5a42da564fbe..6b60dfd80e3d --date=short --no-merges --format='%ad %ae %s'
2019-10-04 cnorthrop@google.com Vulkan: Remove image views forced to one mip level
2019-10-04 geofflang@chromium.org GL: Update RenderbufferGL to use ANGLE_GL_TRY.
2019-10-04 geofflang@chromium.org GL: Fix support for glCopyTextureCHROMIUM with source rectangle textures.

Created with:
  gclient setdep -r src/third_party/angle@6b60dfd80e3d

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 cwallez@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_optional_gpu_tests_rel
TBR=cwallez@google.com

Bug: chromium:990368
Change-Id: Icb5a13f09e5db77d285c5fd38776e766131b2b64
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1841714Reviewed-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@{#702961}

DEPS

@@ -179,7 +179,7 @@ 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': '5a42da564fbea81aa7c6943ca30bb69ed295cc3b',
+  'angle_revision': '6b60dfd80e3dc3fe13eb1b9bcaf8b36f30e20b45',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.