Roll Dart SDK from 906f23c1cb20 to 12c5efc94edf (1 revision) (flutter/engine#48157)

https://dart.googlesource.com/sdk.git/+log/906f23c1cb20..12c5efc94edf

2023-11-16 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.3.0-144.0.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,jonahwilliams@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://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

DEPS

@@ -59,7 +59,7 @@ 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': '906f23c1cb20b46f0ac0ec8c60933703702914f8',
+  'dart_revision': '12c5efc94edf6bffae3f478e62844ec270e78ef0',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

engine/src/flutter/ci/licenses_golden/licenses_dart

@@ -1,4 +1,4 @@
-Signature: 7a940662012cd80c6c394852923febfe
+Signature: a31179e5492243b273640a4e0fc548a2
 
 ====================================================================================================
 LIBRARY: dart