Roll SPIRV-Tools from df859f77dab3 to b4c4da3e7606 (2 revisions)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/df859f77dab3..b4c4da3e7606

2020-08-13 alanbaker@google.com Improve non-semantic instruction handling in the optimizer (#3693)
2020-08-13 vasniktel@gmail.com Fix the bug (#3680)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/spirv-tools-chromium-autoroll
Please CC radial-bots+chrome-roll@google.com,ynovikov@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_angle_vk32_deqp_rel_ng;luci.chromium.try:android_angle_vk32_rel_ng;luci.chromium.try:android_angle_vk64_deqp_rel_ng;luci.chromium.try:android_angle_vk64_rel_ng;luci.chromium.try:linux_angle_deqp_rel_ng;luci.chromium.try:linux-angle-rel;luci.chromium.try:win-angle-rel-32;luci.chromium.try:win-angle-rel-64;luci.chromium.try:win-angle-deqp-rel-32;luci.chromium.try:win-angle-deqp-rel-64
Tbr: radial-bots+chrome-roll@google.com,ynovikov@google.com
Change-Id: I62a79cab9ab50e60dd910c68d356e8d3d44729a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2355586Reviewed-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@{#798080}

DEPS

@@ -302,7 +302,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'spv_tools_revision': 'df859f77dab392dbc78c213d36ba19216b3d068e',
+  'spv_tools_revision': 'b4c4da3e76065180a7c5ce4ac6e5346e58833335',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.