Remove redundant Paint.setARGB in favor of assigning to Paint.color.

sky/examples/raw/hello_world.dart

Index: sky/examples/raw/hello_world.dart
diff --git a/sky/examples/raw/hello_world.dart b/sky/examples/raw/hello_world.dart
index 61079b5927d1499bed8cffd54005c272ee6beb60..7e8e342bf2bf3a10ca759cd97ca33803e01e400f 100644
--- a/sky/examples/raw/hello_world.dart
+++ b/sky/examples/raw/hello_world.dart
@@ -12,7 +12,7 @@ Picture draw(int a, int r, int g, int b) {
   PictureRecorder recorder = new PictureRecorder(width, height);
   double radius = min(width, height) * 0.45;
 
-  Paint paint = new Paint()..setARGB(a, r, g, b);
+  Paint paint = new Paint()..color = Color.fromARGB(a, r, g, b);
   recorder.drawCircle(width / 2, height / 2, radius, paint);
   return recorder.endRecording();
 }