[co19] Roll co19 to 6d2a3c5c20b77475cae2c6c70ff62b1d2c55672e

2024-12-19 sgrekhov22@gmail.com dart-lang/co19#2976. Add equality tests. Part 1. (dart-lang/co19#3021)
2024-12-19 sgrekhov22@gmail.com dart-lang/co19#2559. Add more augmented expression tests for class-like declarations (dart-lang/co19#3019)
2024-12-18 sgrekhov22@gmail.com Fix Finalizer_A01_t04.dart test (dart-lang/co19#3020)
2024-12-18 sgrekhov22@gmail.com dart-lang/co19#2559. Fix metadata tests (dart-lang/co19#3018)
2024-12-17 sgrekhov22@gmail.com dart-lang/co19#2559. Add metadata tests. Part 1. (dart-lang/co19#3017)
2024-12-16 sgrekhov22@gmail.com dart-lang/co19#2559. Add more augmented expression tests (dart-lang/co19#3016)
2024-12-16 sgrekhov22@gmail.com dart-lang/co19#2559. Add tests for reserved word `augmented` in constructors. Part 2. (dart-lang/co19#3015)

Cq-Include-Trybots: luci.dart.try:analyzer-linux-release-try
Change-Id: Idf2d4813fdca6d4107ee17d508cf5f8b27b1b4ff
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/401882
Commit-Queue: Alexander Thomas <athom@google.com>
Reviewed-by: Erik Ernst <eernst@google.com>
Reviewed-by: Alexander Thomas <athom@google.com>

DEPS

@@ -54,7 +54,7 @@ vars = {
 
   # co19 is a cipd package automatically generated for each co19 commit.
   # Use tests/co19/update.sh to update this hash.
-  "co19_rev": "8aa677577f4a2d4edd99f1bd4e3ec554c3712edb",
+  "co19_rev": "6d2a3c5c20b77475cae2c6c70ff62b1d2c55672e",
 
   # The internal benchmarks to use. See go/dart-benchmarks-internal
   "benchmarks_internal_rev": "3bd6bc6d207dfb7cf687537e819863cf9a8f2470",