Roll src/third_party/SPIRV-Tools/src f31f26f73930..b334829a91d6 (4 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/f31f26f73930..b334829a91d6

git log f31f26f73930..b334829a91d6 --date=short --first-parent --format='%ad %ae %s'
2019-11-27 alanbaker@google.com Validate nested constructs (#3068)
2019-11-27 afdx@google.com spirv-fuzz: Improve debugging facilities (#3074)
2019-11-27 stevenperron@google.com Handle unreachable block when computing register pressure (#3070)
2019-11-27 greg@lunarg.com Improve RegisterSizePasses (#3059)

Created with:
  gclient setdep -r src/third_party/SPIRV-Tools/src@b334829a91d6

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,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_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
Bug: None
Tbr: radial-bots+chrome-roll@google.com,cwallez@google.com
Change-Id: Icdd00288d9b8aae1525df0f2089e6ea7ad99913c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1941281Reviewed-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@{#719925}

DEPS

@@ -287,7 +287,7 @@ 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': 'f31f26f739309882b476ad8f3e6fa82a81d91568',
+  'spv_tools_revision': 'b334829a91d6bcbbf6e101ca54adccb113a24fa9',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.