Roll Tint from c76ec15b45 to 6f7986d9b5 (15 revisions)

https://dawn.googlesource.com/tint.git/+log/c76ec15b4589..6f7986d9b543

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/tint-dawn
Please CC jrprice@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

Bug: None
Tbr: jrprice@google.com
Change-Id: I6cfa868d9bb6d6018cdd3467d95a29dafb5a1713
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/47460
Reviewed-by: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: Dawn Autoroller <dawn-autoroll@skia-public.iam.gserviceaccount.com>

DEPS

@@ -96,7 +96,7 @@ deps = {
 
   # WGSL support
   'third_party/tint': {
-    'url': '{dawn_git}/tint@c76ec15b4589ba5359789027e78951958102dfe1',
+    'url': '{dawn_git}/tint@6f7986d9b543b2654b30201eb46da259758bee75',
   },
 
   # GLFW for tests and samples