Roll Dart SDK from 54322a0b1109 to 204db085d970 (3 revisions) (flutter#181890)

https://dart.googlesource.com/sdk.git/+log/54322a0b1109..204db085d970

2026-02-04 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.12.0-109.0.dev
2026-02-04 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.12.0-108.0.dev
2026-02-03 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.12.0-107.0.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
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:
https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Author: engine-flutter-autoroll

DEPS

@@ -59,7 +59,7 @@ vars = {
   # updated revision list of existing dependencies. You will need to
   # gclient sync before and after update deps to ensure all deps are updated.
   # updated revision list of existing dependencies.
-  'dart_revision': '54322a0b11097633bbe5c0073995868419ffcb47',
+  'dart_revision': '204db085d970ed3bda52afccdc78ca14b01b78de',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -317,7 +317,7 @@ deps = {
    Var('dart_git') + '/dart_style.git@f624489a5013ec58de469d4fd8793c283f62b5d8',
 
   'engine/src/flutter/third_party/dart/third_party/pkg/dartdoc':
-   Var('dart_git') + '/dartdoc.git@03f48ee08eccdcf2e4cd06678501f07c182bebf5',
+   Var('dart_git') + '/dartdoc.git@af0085039035557c792b2d08965e24c2dd342d63',
 
   'engine/src/flutter/third_party/dart/third_party/pkg/ecosystem':
    Var('dart_git') + '/ecosystem.git' + '@' + Var('dart_ecosystem_rev'),