Change the ColorFilter constructor to ColorFilter.Mode, in case we want to add

sky/examples/raw/painting.sky

Index: sky/examples/raw/painting.sky
diff --git a/sky/examples/raw/painting.sky b/sky/examples/raw/painting.sky
index 76da471c67e4b6058521110f9f6952d911f88feb..9e2b84079c6bedd82f860365d5606a5d900cff62 100644
--- a/sky/examples/raw/painting.sky
+++ b/sky/examples/raw/painting.sky
@@ -56,8 +56,8 @@ void main() {
             (Paint layerPaint) {
           layerPaint.color = const Color.fromARGB(128, 255, 255, 0);
           layerPaint.setColorFilter(
-              new ColorFilter(const Color.fromARGB(128, 0, 0, 255),
-                              TransferMode.srcInMode));
+              new ColorFilter.Mode(const Color.fromARGB(128, 0, 0, 255),
+                                   TransferMode.srcInMode));
           layerPaint.setMaskFilter(
               new MaskFilter.Blur(BlurStyle.normal, 3.0, highQuality: true));
         })