Re-land "Add a Color class to dart:sky."

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 7b8ac0f8eaa210ebdf5889441a153baf45858fad..765f3c5d64b8af8f736a8a23ffa7e0e625f22dc7 100644
--- a/sky/engine/bindings/scripts/dart_types.py
+++ b/sky/engine/bindings/scripts/dart_types.py
@@ -114,7 +114,9 @@ CPP_SPECIAL_CONVERSION_RULES = {
     'boolean': 'bool',
     'unrestricted double': 'double',
     'unrestricted float': 'float',
-    'Rect': 'Rect',  # Pass Rect by value, not pointer.
+    # Pass these by value, not pointer.
+    'Rect': 'Rect',
+    'Color': 'CanvasColor',
 }
 
 
@@ -354,6 +356,7 @@ DART_TO_CPP_VALUE = {
     # We should handle it automatically, but map to a String for now.
     'StorageType': 'DartUtilities::dartToString(args, {index}, exception, {auto_scope})',
     'Rect': 'DartConverter<{implemented_as}>::FromArguments{null_check}(args, {index}, exception)',
+    'Color': 'DartConverter<CanvasColor>::FromArguments{null_check}(args, {index}, exception)',
 }
 
 
@@ -618,6 +621,7 @@ DART_SET_RETURN_VALUE = {
     # Typed arrays don't have special Dart* classes for Dart.
     'ArrayBuffer': 'Dart_SetReturnValue(args, DartUtilities::arrayBufferToDart({cpp_value}))',
     'TypedList': 'Dart_SetReturnValue(args, DartUtilities::arrayBufferViewToDart({cpp_value}))',
+    'Color': 'DartConverter<CanvasColor>::SetReturnValue(args, {cpp_value})',
 }