Roll src/third_party/SPIRV-Tools/src ec12de913124..42f885238114 (3 commits)

https://chromium.googlesource.com/external/github.com/KhronosGroup/SPIRV-Tools.git/+log/ec12de913124..42f885238114

git log ec12de913124..42f885238114 --date=short --no-merges --format='%ad %ae %s'
2019-10-28 bclayton@google.com utils: Add a vscode extension for SPIR-V disassembly files (#2987)
2019-10-28 greg@lunarg.com Add two new simplifications. (#2984)
2019-10-28 afdx@google.com spirv-fuzz: Transformation to extract from a composite object (#2991)

Created with:
  gclient setdep -r src/third_party/SPIRV-Tools/src@42f885238114

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/+/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

Bug: None
Change-Id: I275ca1123d678df4b9688c7bfcb5a09ede232114
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1886510Reviewed-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@{#710258}

DEPS

@@ -291,7 +291,7 @@ 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': 'ec12de9131244a076c34ddca2e8d7451288be7e1',
+  'spv_tools_revision': '42f88523811412f68553fbc37223802ac4eb09a1',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.