Roll Dart SDK from 2fc9f4dd9623 to 7f6fabbe9fba (1 revision) (flutter/engine#42090)

https://dart.googlesource.com/sdk.git/+log/2fc9f4dd9623..7f6fabbe9fba

2023-05-17 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.1.0-118.0.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://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

DEPS

@@ -53,7 +53,7 @@ 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': '2fc9f4dd962384fab8178855ae33078b695744f1',
+  'dart_revision': '7f6fabbe9fbab42ce92f62fe84ada2925fb8ef8f',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -465,7 +465,7 @@ deps = {
    Var('dart_git') + '/term_glyph.git@3de5f1b6b07c3e713ff5d0ab6e4305b0403d7162',
 
   'src/third_party/dart/third_party/pkg/test':
-   Var('dart_git') + '/test.git@931410c860340456847f0f33aaa0777f93dc23d5',
+   Var('dart_git') + '/test.git@8e444dfa269c42a76fd96dbf9547bd01013154f6',
 
   'src/third_party/dart/third_party/pkg/test_reflective_loader':
    Var('dart_git') + '/test_reflective_loader.git@d1b763f6281a46a48e1da6f0a6e8152e3480e8d2',