Roll Dawn from 268fe254ec50 to 2ffc55ab385d (1 revision)

https://dawn.googlesource.com/dawn.git/+log/268fe254ec50..2ffc55ab385d

2020-07-01 jiajie.hu@intel.com Never try to populate the LASTCHANGE file in non-standalone checkout

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dawn-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/+doc/master/autoroll/README.md

Cq-Include-Trybots: luci.chromium.try:dawn-linux-x64-deps-rel;luci.chromium.try:dawn-mac-x64-deps-rel;luci.chromium.try:dawn-win10-x64-deps-rel;luci.chromium.try:dawn-win10-x86-deps-rel
Bug: None
Tbr: cwallez@google.com
Change-Id: Iafb3ccb79f93815104ca5be9569a7e96216f5710
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2277603Reviewed-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@{#784377}

DEPS

@@ -311,7 +311,7 @@ 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': '268fe254ec50a72b28b03017c63044a8ecbe92ba',
+  'dawn_revision': '2ffc55ab385d5a6e4bb4c6b261692842574d771e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.