Roll src/third_party/dart 6ff8d2199d..327bc451f8 (12 commits)

dart-lang/sdk@327bc451f8 Added variance support in listeners to ast.
dart-lang/sdk@07db94d454 Add support for details and implement some initial details for regions
dart-lang/sdk@f3793ab22d [tools] Update generate_idefiles.py to exclude analyzing sdk_nnbd
dart-lang/sdk@661816ea06 Use Context.separator in nnbd i13n output; Fixes flutter#38574
dart-lang/sdk@38a3a6b6cb Don't use '.type' in TypeParameterMember.
dart-lang/sdk@3c18db7d9e update analyzer error message generator to generate hasPublishedDocs
dart-lang/sdk@5c5a76078e [dartdevc] improve escaping to handle kernel extension symbols
dart-lang/sdk@44da8af04f Reland "[vm, compiler] Reduce alignment of Instructions and remove some debugging trap instructions."
dart-lang/sdk@87d795c177 fix formatting
dart-lang/sdk@88f35f8319 [infra] Update checked in SDKs to 2.6.0-dev.3.0
dart-lang/sdk@2741022aa0 [vm/http] replace hard coded string in http headers
dart-lang/sdk@d2c0bffde3 Bump analyzer_plugin's maximum supported analyzer version

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': '6ff8d2199da265e0aa2e3ca0b677956db3d42231',
+  'dart_revision': '327bc451f8397f393808454ff65ee09bc2cb18ed',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -377,7 +377,7 @@ deps = {
    Var('dart_git') + '/package_resolver.git' + '@' + Var('dart_package_resolver_tag'),
 
   'src/third_party/dart/tools/sdks':
-   {'packages': [{'version': 'version:2.5.0', 'package': 'dart/dart-sdk/${{platform}}'}], 'dep_type': 'cipd'},
+   {'packages': [{'version': 'version:2.6.0-dev.3.0', 'package': 'dart/dart-sdk/${{platform}}'}], 'dep_type': 'cipd'},
 
   # WARNING: end of dart dependencies list that is cleaned up automatically - see create_updated_flutter_deps.py.
 

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 8ccdc63b9d5cb0812e1e8d6c67002c0a
+Signature: d920708b7014221342642984463a42b6
 
 UNUSED LICENSES: