Revert "Roll src/third_party/dart 6e2b3f0326..b99df2be86 (5 commits) (#11287)" (#11297)

This reverts commit df31dba4.

DEPS

@@ -34,7 +34,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'b99df2be860490e6825a8f2e16eb4b2fd7a33b9e',
+  'dart_revision': '6e2b3f0326bc15ad938319cbbb151f183d064609',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -72,7 +72,7 @@ vars = {
   'dart_mustache_tag': '5e81b12215566dbe2473b2afd01a8a8aedd56ad9',
   'dart_oauth2_tag': '1.2.1',
   'dart_observatory_pub_packages_rev': '0894122173b0f98eb08863a7712e78407d4477bc',
-  'dart_package_config_tag': '2453cd2e78c2db56ee2669ced17ce70dd00bf576',
+  'dart_package_config_tag': '1.0.5',
   'dart_package_resolver_tag': '1.0.10',
   'dart_path_tag': '1.6.2',
   'dart_pedantic_tag': 'v1.8.0',

ci/licenses_golden/licenses_third_party

-Signature: 94bb4276408984fa58f0cf5fe27bc7bd
+Signature: 5b79ad77f8b89f4b9c8c5a94fca653cb
 
 UNUSED LICENSES: