Roll Tint from b3becb2f257a to 685cb02ea8d9 (5 revisions)

https://dawn.googlesource.com/tint.git/+log/b3becb2f257a..685cb02ea8d9

2020-12-02 dsinclair@chromium.org Remove internal usage of Context.
2020-12-02 dsinclair@chromium.org [ast] Remove more set methods.
2020-12-02 bclayton@google.com Unrevert "[ast] Remove unused constructors and setters".
2020-12-02 bclayton@google.com Add ClassID::Unique template and TINT_INSTANTIATE_CLASS_ID
2020-12-02 enga@chromium.org spirv-reader: Fix bug with passing stack-allocated variable

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 dsinclair@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: dsinclair@google.com
Change-Id: I85b4681a00284c75a1e5ede40ae0644abd09054c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570021Reviewed-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@{#833150}

DEPS

@@ -369,7 +369,7 @@ vars = {
   'ukey2_revision': '0275885d8e6038c39b8a8ca55e75d1d4d1727f47',
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'tint_revision': 'b3becb2f257acf1decb8f7605d9f547ad891ed88',
+  'tint_revision': '685cb02ea8d9afbad46d52ccbe4fa3728ac37693',
 
   # TODO(crbug.com/941824): The values below need to be kept in sync
   # between //DEPS and //buildtools/DEPS, so if you're updating one,