Roll Dart SDK from 9506d0c9f5ef to 8f49edfb6989 (1 revision) (#43665)

https://dart.googlesource.com/sdk.git/+log/9506d0c9f5ef..8f49edfb6989

2023-07-13 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.1.0-309.0.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': '9506d0c9f5ef12ed2f161006165290c5e86d19cc',
+  'dart_revision': '8f49edfb69898373949135d7f317217ab1acb336',
 
   # 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_third_party

@@ -1,4 +1,4 @@
-Signature: 28f3d38d110f51b67e3777c18492d67f
+Signature: 92da6c802dde52d98bba3a59e106b667
 
 ====================================================================================================
 LIBRARY: angle