Roll src/third_party/dawn 91b2142ee44d..9e64afcb91f7 (2 commits)

https://dawn.googlesource.com/dawn.git/+log/91b2142ee44d..9e64afcb91f7

git log 91b2142ee44d..9e64afcb91f7 --date=short --no-merges --format='%ad %ae %s'
2019-10-10 rharrison@chromium.org Rolling 4 dependencies
2019-10-10 beaufort.francois@gmail.com Allow Bind Group Layout Binding visibility to be None

Created with:
  gclient setdep -r src/third_party/dawn@9e64afcb91f7

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
TBR=cwallez@google.com

Bug: None
Change-Id: I981feaa8d7699d5cfe20f1e5c69dbc027c829152
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1852149Reviewed-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@{#704665}

DEPS

@@ -302,7 +302,7 @@ 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': '91b2142ee44d3e4eb3bafcbc8eec4d196006c9d3',
+  'dawn_revision': '9e64afcb91f74e75a16fa5639d272c5c2a536bc6',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.