Roll Dart SDK from bff9c6ff642d to 23701722ca9e (2 revisions) (#55551)

https://dart.googlesource.com/sdk.git/+log/bff9c6ff642d..23701722ca9e

2024-10-01 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.6.0-306.0.dev
2024-10-01 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com Version 3.6.0-305.0.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,matanl@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
https://dart.googlesource.com/external/github.com/flutter/engine/+/ef0f47d299533eabcf3398e819a953f85a1bc9d5
diff --git a/DEPS b/DEPS
index 760d42d..4d16392 100644
--- a/DEPS
+++ b/DEPS
@@ -280,7 +280,7 @@
 deps = {
   'engine/src': 'https://github.com/flutter/buildroot.git' + '@' + 'f85c3be4bf808add6ba867b8ff7943fd235b7b5e',
 
-  'engine/src/flutter': Var('flutter_git') + '/mirrors/engine' + '@' + 'da28db8ff41db5da266c493ce14ffdcdcac70470',
+  'engine/src/flutter': Var('flutter_git') + '/mirrors/engine' + '@' + 'ef0f47d299533eabcf3398e819a953f85a1bc9d5',
 
   'engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + '7bb6899a2c493b7946ce7ac6290c43050e6068b1',
 
diff --git a/commits.json b/commits.json
index 6f4e61a..7111481 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
-  "engine/src/flutter":"da28db8ff41db5da266c493ce14ffdcdcac70470",
+  "engine/src/flutter":"ef0f47d299533eabcf3398e819a953f85a1bc9d5",
   "engine/src/flutter/third_party/dart":"7bb6899a2c493b7946ce7ac6290c43050e6068b1",
   "flutter":"9e88a28221b16673e5f0d5df05050918a2be7e9e"
 }
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