Fix bustage from my previous CL: "Color.fromARGB" becomes "new Color.fromARGB".

sky/examples/raw/custom_paint_without_element.sky

 <script>
 import "dart:math";
 import 'dart:sky';
 
 void main() {
   double width = window.innerWidth.toDouble();
   double height = window.innerHeight.toDouble();
 
   PictureRecorder recorder = new PictureRecorder(width, height);
   double radius = min(width, height) * 0.45;
 
-  Paint paint = new Paint()..color = Color.fromARGB(255, 0, 255, 0);
+  Paint paint = new Paint()..color = const Color.fromARGB(255, 0, 255, 0);
 
   recorder.drawCircle(width / 2, height / 2, radius, paint);
 
   document.rootPicture = recorder.endRecording();
 }
 </script>