Use an enum for Dart bindings for Skia Paint style

sky/engine/bindings/scripts/dart_types.py

Index: sky/engine/bindings/scripts/dart_types.py
diff --git a/sky/engine/bindings/scripts/dart_types.py b/sky/engine/bindings/scripts/dart_types.py
index d1f07db17ff4acd8163cd5c88f985b20c3100536..11f10578c9176d6fd1a7f076d27799bfecf03cce 100644
--- a/sky/engine/bindings/scripts/dart_types.py
+++ b/sky/engine/bindings/scripts/dart_types.py
@@ -120,6 +120,7 @@ CPP_SPECIAL_CONVERSION_RULES = {
     'Point': 'Point',
     'Rect': 'Rect',
     'TransferMode': 'SkXfermode::Mode',
+    'PaintingStyle': 'SkPaint::Style',
 }
 
 
@@ -368,6 +369,7 @@ DART_TO_CPP_VALUE = {
     'Point': pass_by_value_format('{implemented_as}'),
     'Rect': pass_by_value_format('{implemented_as}'),
     'TransferMode': pass_by_value_format('TransferMode'),
+    'PaintingStyle': pass_by_value_format('PaintingStyle'),
 }