Fix up constructor naming style for MaskFilter and ColorFilter.

sky/sdk/lib/framework/painting/shadows.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:sky' as sky;
 
 /// Helper class to build a Paint DrawLooper that adds shadows to the Paint's
 /// operation.
 class ShadowDrawLooperBuilder {
   var builder_ = new sky.LayerDrawLooperBuilder();
 
   void addShadow(sky.Size offset, sky.Color color, double blur) {
     builder_.addLayerOnTop(
           new sky.DrawLooperLayerInfo()
             ..setPaintBits(-1)
             ..setOffset(offset.toPoint())
             ..setColorMode(sky.TransferMode.srcMode),
           (sky.Paint layerPaint) {
         layerPaint.color = color;
         layerPaint.setMaskFilter(
-          new sky.MaskFilter.Blur(sky.BlurStyle.normal,
+          new sky.MaskFilter.blur(sky.BlurStyle.normal,
                                   blur,
                                   highQuality: true));
       });
   }
 
   sky.DrawLooper build() {
     builder_.addLayerOnTop(new sky.DrawLooperLayerInfo(), (_) {});
     return builder_.build();
   }
 }