Roll Dart SDK from 675c716 to 5c59a47 (1 revision) (#21952)

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': '675c7165c071c405d6496c8f6cf411721ad7794a',
+  'dart_revision': '5c59a47beda7af5114881b23a8238aeb99338654',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py