Roll Dart SDK from 7cbcf48 to 6f5478a (2 revisions)

https://dart.googlesource.com/sdk.git/+log/7cbcf48157cf..6f5478a58387

2022-11-14 [email protected] Version 2.19.0-398.0.dev
2022-11-14 [email protected] Version 2.19.0-397.0.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 [email protected],[email protected] 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': '7cbcf48157cf7324ca36ba3070d80a4abe205eb7',
+  'dart_revision': '6f5478a5838705ad74859cb179127cb4c65baa7c',
 
   # 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: f605759571f528a9c8fee0b3b7fd6cd0
+Signature: 3edfee755dd8cf9a49fd787175b6d2ec
 
 UNUSED LICENSES: