Roll Dawn from 5b6c1ebce7c6 to b86e45f8ca87 (6 revisions)

https://dawn.googlesource.com/dawn.git/+log/5b6c1ebce7c6..b86e45f8ca87

2021-06-17 cwallez@chromium.org Omit types in most WGSL `var` statements.
2021-06-17 bclayton@google.com wgsl: Suppress all VertexFormatTests when using FXC
2021-06-17 cwallez@chromium.org Add SetIndex/VertexBuffer offset argument alignment constraints
2021-06-17 cwallez@chromium.org WireCmd: disallow optional members with length="otherMember"
2021-06-17 bclayton@google.com wgsl: Fixes for new validation failures
2021-06-17 jrprice@google.com Metal: Remap vertex buffers when using Tint

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dawn-skia-autoroll
Please CC alanbaker@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: skia/skia.primary:Build-Debian10-Clang-x86_64-Debug-Dawn
Bug: None
Tbr: alanbaker@google.com
Change-Id: I15f98d4c7e175247c28fbf0b8ec4dde9d01a46f9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/419657
Reviewed-by: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: skia-autoroll <skia-autoroll@skia-public.iam.gserviceaccount.com>
diff --git a/DEPS b/DEPS
index 0715268..8a93efa 100644
--- a/DEPS
+++ b/DEPS
@@ -16,7 +16,7 @@
   "third_party/externals/d3d12allocator"  : "https://skia.googlesource.com/external/github.com/GPUOpen-LibrariesAndSDKs/D3D12MemoryAllocator.git@169895d529dfce00390a20e69c2f516066fe7a3b",
   # Dawn requires jinja2 and markupsafe for the code generator, and tint for SPIRV compilation.
   # When the Dawn revision is updated these should be updated from the Dawn DEPS as well.
-  "third_party/externals/dawn"            : "https://dawn.googlesource.com/dawn.git@5b6c1ebce7c6c15ceadbf0df145a866b7453c1c4",
+  "third_party/externals/dawn"            : "https://dawn.googlesource.com/dawn.git@b86e45f8ca873b7441abf3e4f4ad344b1c204484",
   "third_party/externals/jinja2"          : "https://chromium.googlesource.com/chromium/src/third_party/jinja2@a82a4944a7f2496639f34a89c9923be5908b80aa",
   "third_party/externals/markupsafe"      : "https://chromium.googlesource.com/chromium/src/third_party/markupsafe@0944e71f4b2cb9a871bcbe353f95e889b64a611a",
   "third_party/externals/tint"            : "https://dawn.googlesource.com/tint@944c5617caa63794dc8d82a4a18ad9094dd98538",