Roll src/third_party/dawn 1249ada986fc..5a921f8fadba (2 commits)

https://dawn.googlesource.com/dawn.git/+log/1249ada986fc..5a921f8fadba

git log 1249ada986fc..5a921f8fadba --date=short --first-parent --format='%ad %ae %s'
2020-02-24 cwallez@chromium.org Roll third_party/swiftshader/ 8def9063c..bdfcfe9cf (11 commits)
2020-02-24 rharrison@chromium.org Rolling 4 dependencies

Created with:
  gclient setdep -r src/third_party/dawn@5a921f8fadba

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/+/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: I54dee66cd6eddc762100cc0164fda88a2e05fd03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2070979Reviewed-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@{#744154}

DEPS

@@ -298,7 +298,7 @@ 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': '1249ada986fc62a95439b8c8ec805fd3dff1e46d',
+  'dawn_revision': '5a921f8fadbaef0660024f6ac2fe3b4f9bdb02ea',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.