Roll Dart SDK from 5278383 to b43baaa (723 revisions) (#22265)

Author: skia-flutter-autoroll

DEPS

@@ -34,7 +34,7 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/master/DEPS.
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': '52783837369de45d3372cb6c6b7cdd63e71cd829',
+  'dart_revision': 'b43baaaa477d546a92535d3372befaf6259f526a',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
@@ -43,7 +43,7 @@ vars = {
   'dart_boringssl_rev': '4dfd5af70191b068aebe567b8e29ce108cee85ce',
   'dart_clock_rev': 'a494269254ba978e7ef8f192c5f7fec3fc05b9d3',
   'dart_collection_rev': 'e4bb038ce2d8e66fb15818aa40685c68d53692ab',
-  'dart_dart_style_tag': '1.3.8+1',
+  'dart_dart_style_tag': '1.3.9',
   'dart_http_retry_tag': '0.1.1',
   'dart_http_throttle_tag': '1.0.2',
   'dart_intl_tag': '0.17.0-nullsafety',