Revert Dart SDK back to be8a95b6717d (#48799)

See #139755

Author: jason-simmons

DEPS

@@ -59,7 +59,7 @@ 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': 'b6d5e010d2c56b0b196fdff1c64442c2d1fd1d0c',
+  'dart_revision': 'be8a95b6717d9a9e55752655a289994fde42f4b1',
 
   # 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_dart

@@ -1,4 +1,4 @@
-Signature: 7b0eee0f9a3783df2054d9aa304efd63
+Signature: ae182e4e10a0bacf95bbd4a9475a970c
 
 ====================================================================================================
 LIBRARY: dart