Roll Dart SDK from 68d8b0f58be7 to 5a173adb22ed (1 revision) (#38525)

https://dart.googlesource.com/sdk.git/+log/68d8b0f58be7..5a173adb22ed

2022-12-28 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.0.0-67.0.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,garyq@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

Author: skia-flutter-autoroll

DEPS

@@ -48,7 +48,7 @@ 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': '68d8b0f58be72a4331580a26a00beaf95222867f',
+  'dart_revision': '5a173adb22ed3fe8887b8216cf6833a211317b4c',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -451,7 +451,7 @@ deps = {
    Var('dart_git') + '/watcher.git' + '@' + Var('dart_watcher_rev'),
 
   'src/third_party/dart/third_party/pkg/web_socket_channel':
-   Var('dart_git') + '/web_socket_channel.git@1b0561cfec8ff7e9465896eb340ea3c382b59393',
+   Var('dart_git') + '/web_socket_channel.git@a90e740dad4739d578e09eb0e076ac2846f9404e',
 
   'src/third_party/dart/third_party/pkg/webdev':
    Var('dart_git') + '/webdev.git' + '@' + Var('dart_webdev_rev'),