Reverts "Roll Dart SDK from b7cad2edae4b to 673b3aa8558a (1 revision) (#52677)" (#52683)

Reverts: #52677
Initiated by: zanderso
Reason for reverting: Failed roll to framework in flutter/flutter#147999
Original PR Author: skia-flutter-autoroll

Reviewed By: {fluttergithubbot}

This change reverts the following previous change:

https://dart.googlesource.com/sdk.git/+log/b7cad2edae4b..673b3aa8558a

2024-05-08 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.5.0-139.0.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,zra@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

Author: auto-submit[bot]

DEPS

@@ -56,7 +56,7 @@ 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': '673b3aa8558a4af94a6c9f424b7c4569899bef9b',
+  'dart_revision': 'b7cad2edae4bcbe05332c9956a04692d19798904',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -434,7 +434,7 @@ deps = {
    Var('dart_git') + '/mockito.git@81ecb88b631a9c1e677852a33ad916238dee0ef2',
 
   'src/flutter/third_party/dart/third_party/pkg/native':
-   Var('dart_git') + '/native.git@a152cfa21129510e9227962a01ec12918e192ecc',
+   Var('dart_git') + '/native.git@71ada4b5c8001e6b8207ed40331d158e0912cd94',
 
   'src/flutter/third_party/dart/third_party/pkg/package_config':
    Var('dart_git') + '/package_config.git@a36e496d61937a800c22f68035dc98bf8ead7fb2',