Roll Tint from ccc67252ffa4 to 4226b6a1d8bf (7 revisions)

https://dawn.googlesource.com/tint.git/+log/ccc67252ffa4..4226b6a1d8bf

2020-12-11 dsinclair@chromium.org Add Symbol to alias.
2020-12-11 dsinclair@chromium.org Add a symbol to the Identifier AST node
2020-12-11 dneto@google.com spirv-reader: refactor, add ToI32 helper
2020-12-11 dsinclair@chromium.org Add a demangler
2020-12-11 dsinclair@chromium.org Add a symbol to the Function AST node.
2020-12-11 dneto@google.com spirv-reader: Support multisampled textures
2020-12-11 bclayton@google.com ast: Merge DecoratedVariable into 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 rharrison@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: rharrison@google.com
Change-Id: I9d45cf7cfdfb89b15e9d4df07b3ac40a8c818f80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2587223Reviewed-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@{#836354}

DEPS

@@ -365,7 +365,7 @@ vars = {
   'ukey2_revision': '0275885d8e6038c39b8a8ca55e75d1d4d1727f47',
   # the commit queue can handle CLs rolling feed
   # and whatever else without interference from each other.
-  'tint_revision': 'ccc67252ffa40dd723f0c114ac8906b3ad13b063',
+  'tint_revision': '4226b6a1d8bfa4add00f199c54a2c6d726a3ca57',
 
   # TODO(crbug.com/941824): The values below need to be kept in sync
   # between //DEPS and //buildtools/DEPS, so if you're updating one,