Roll Dart SDK from cc7a770 to dc20e31 (2 revisions)

https://dart.googlesource.com/sdk.git/+log/cc7a770ed1d9..dc20e31ba74c

2022-10-26 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 2.19.0-342.0.dev
2022-10-26 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 2.19.0-341.0.dev

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter-engine
Please CC dart-vm-team@google.com,jsimmons@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Flutter Engine: https://github.com/flutter/flutter/issues/new/choose

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/main/autoroll/README.md

Author: skia-flutter-autoroll

DEPS

@@ -43,7 +43,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/main/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'cc7a770ed1d993ef3e6aec99f58dd506acb03278',
+  'dart_revision': 'dc20e31ba74c445dadd77fcc608311c69116cce9',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -214,7 +214,7 @@ deps = {
    Var('dart_git') + '/dart_style.git@f79a9828ad07e50d6e8352ac154cc16eb4d78d5c',
 
   'src/third_party/dart/third_party/pkg/dartdoc':
-   Var('dart_git') + '/dartdoc.git@8878245e0766bc943955e3e3883832251e48d95d',
+   Var('dart_git') + '/dartdoc.git@4902beaa24bd153252e3a83d62dd9bc8887dac01',
 
   'src/third_party/dart/third_party/pkg/ffi':
    Var('dart_git') + '/ffi.git@fb5f2667826c0900e551d19101052f84e35f41bf',

ci/licenses_golden/licenses_third_party

@@ -1,4 +1,4 @@
-Signature: 073bf3be567deaef937fac2e6837d81b
+Signature: db07a0f32b0efc60ab748191d2080f97
 
 UNUSED LICENSES: