Roll src/third_party/dawn 596d6fe00db7..ac71e34d4ad1 (4 commits)

https://dawn.googlesource.com/dawn.git/+log/596d6fe00db7..ac71e34d4ad1


git log 596d6fe00db7..ac71e34d4ad1 --date=short --no-merges --format='%ad %ae %s'
2018-11-28 brandon1.jones@intel.com Change Copy Operation Interfaces to Match WebGPU IDL
2018-11-28 enga@chromium.org Factor SerialQueue into SerialQueue and SerialMap
2018-11-28 cwallez@chromium.org WireCmd: require opt-in to treat ID 0 as nullptr instead of error.
2018-11-28 cwallez@chromium.org Roll SPIRV-Tools and temporarily use Vulkan SPIRV validation


Created with:
  gclient setdep -r src/third_party/dawn@ac71e34d4ad1

The AutoRoll server is located here: https://autoroll.skia.org/r/dawn-chromium-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel

BUG=chromium:905273,chromium:906418,chromium:908678
TBR=cwallez@chromium.org

Change-Id: I4979c5123a026fa468c660f45dce4fcf4f1903ae
Reviewed-on: https://chromium-review.googlesource.com/c/1354240Reviewed-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@{#611909}

DEPS

@@ -236,7 +236,7 @@ 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.
-  'dawn_revision': '596d6fe00db768f9d723219f98a3f626f333caf8',
+  'dawn_revision': 'ac71e34d4ad130a0374afc9046484a35e008c5e2',
 }
 
 # Only these hosts are allowed for dependencies in this DEPS file.