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

more ColorFilter types.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1163373007.

examples/game/lib/sprite_node.dart

@@ -52,7 +52,7 @@ class SpriteNode extends TransformNode {
       Paint paint = new Paint();
       paint.setARGB((255.0*_opacity).toInt(), 255, 255, 255);
       if (colorOverlay != null) {
-        paint.setColorFilter(new ColorFilter(colorOverlay, TransferMode.srcATopMode));
+        paint.setColorFilter(new ColorFilter.Mode(colorOverlay, TransferMode.srcATopMode));
       }
       if (transferMode != null) {
         paint.setTransferMode(transferMode);

examples/raw/painting.sky

@@ -56,7 +56,7 @@ void main() {
             (Paint layerPaint) {
           layerPaint.color = const Color.fromARGB(128, 255, 255, 0);
           layerPaint.setColorFilter(
-              new ColorFilter(const Color.fromARGB(128, 0, 0, 255),
+              new ColorFilter.Mode(const Color.fromARGB(128, 0, 0, 255),
                                    TransferMode.srcInMode));
           layerPaint.setMaskFilter(
               new MaskFilter.Blur(BlurStyle.normal, 3.0, highQuality: true));