Reverts "Manual roll Dart SDK from d6c08fa9bb54 to 6ff69d6b7f59 (15 r…

…evisions)" (#49852)

Reverts #49825
Initiated by: zanderso
This change reverts the following previous change:
Original Description:

Manual roll requested by aam@google.com

https://dart.googlesource.com/sdk.git/+log/d6c08fa9bb54..6ff69d6b7f59

2024-01-17 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-39.0.dev
2024-01-17 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-38.0.dev
2024-01-16 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-37.0.dev
2024-01-16 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-36.0.dev
2024-01-16 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-35.0.dev
2024-01-16 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-34.0.dev
2024-01-15 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-33.0.dev
2024-01-15 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-32.0.dev
2024-01-15 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-31.0.dev
2024-01-15 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-30.0.dev
2024-01-14 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-29.0.dev
2024-01-13 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-28.0.dev
2024-01-13 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-27.0.dev
2024-01-13 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-26.0.dev
2024-01-12 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.4.0-25.0.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
aam@google.com,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

Co-authored-by: auto-submit[bot] <flutter-engprod-team@google.com>

DEPS

@@ -65,7 +65,7 @@ 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': '6ff69d6b7f5913ab52c97e072dfeac482d794113',
+  'dart_revision': 'd6c08fa9bb54dfc52e32ee879ae157f8a01d5a50',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py

ci/licenses_golden/licenses_dart

@@ -1,4 +1,4 @@
-Signature: 7409de5fbfeb3a60d2310117fe55c60e
+Signature: 60ebc270fcd5313847ed98c6ce909e6a
 
 ====================================================================================================
 LIBRARY: dart
@@ -4707,7 +4707,7 @@ Exhibit B - "Incompatible With Secondary Licenses" Notice
   This Source Code Form is "Incompatible With Secondary Licenses", as
   defined by the Mozilla Public License, v. 2.0.
 
-You may obtain a copy of this library's Source Code Form from: https://dart.googlesource.com/sdk/+/6ff69d6b7f5913ab52c97e072dfeac482d794113
+You may obtain a copy of this library's Source Code Form from: https://dart.googlesource.com/sdk/+/d6c08fa9bb54dfc52e32ee879ae157f8a01d5a50
 /third_party/fallback_root_certificates/
 
 ====================================================================================================

sky/packages/sky_engine/LICENSE

@@ -31204,7 +31204,7 @@ Exhibit B - "Incompatible With Secondary Licenses" Notice
   This Source Code Form is "Incompatible With Secondary Licenses", as
   defined by the Mozilla Public License, v. 2.0.
 
-You may obtain a copy of this library's Source Code Form from: https://dart.googlesource.com/sdk/+/6ff69d6b7f5913ab52c97e072dfeac482d794113
+You may obtain a copy of this library's Source Code Form from: https://dart.googlesource.com/sdk/+/d6c08fa9bb54dfc52e32ee879ae157f8a01d5a50
 /third_party/fallback_root_certificates/
 
 --------------------------------------------------------------------------------