Roll Tint from 1980095da7f4 to 20a8d31849c9 (1 revision)

https://dawn.googlesource.com/tint.git/+log/1980095da7f4..20a8d31849c9

2020-11-12 dsinclair@chromium.org Create an AST builder class.

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/tint-chromium-autoroll
Please CC sarahmashay@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: sarahmashay@google.com
Change-Id: If33ce849b84f9809bc872d0cee70cb636197601d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2535570Reviewed-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@{#827060}

DEPS

@@ -363,7 +363,7 @@ vars = {
   'ukey2_revision': '0275885d8e6038c39b8a8ca55e75d1d4d1727f47',
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'tint_revision': '1980095da7f4325ab474166ab84ebe953afe80c3',
+  'tint_revision': '20a8d31849c93b552becfb7df4182a69d24cbe1b',
 
   # TODO(crbug.com/941824): The values below need to be kept in sync
   # between //DEPS and //buildtools/DEPS, so if you're updating one,