Trivial code style changes in animation code.

sky/sdk/lib/widgets/material.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 'package:sky/animation/animation_performance.dart';
 import 'package:sky/painting/box_painter.dart';
 import 'package:sky/widgets/animated_component.dart';
 import 'package:sky/widgets/animation_builder.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/default_text_style.dart';
@@ skipping 21 matching lines @@
     this.color
   }) : super(key: key) {
     assert(level != null);
   }
 
   Widget child;
   MaterialType type;
   int level;
   Color color;
 
-  AnimationBuilder _builder;
+  final AnimationBuilder _builder = new AnimationBuilder();

[Matt Perry, 2015/07/13 17:32:55]

Wouldn't this cause us to allocate a new object for Materials that we're going
to throw away?

[abarth-chromium, 2015/07/13 17:41:06]

Constructors for final fields are called lazily the first time someone reads
them.

[abarth-chromium, 2015/07/13 17:44:59]

s/Constructors/initializers/

 
   void initState() {
-    _builder = new AnimationBuilder()
+    _builder
       ..shadow = new AnimatedType<double>(level.toDouble())
       ..backgroundColor = _getBackgroundColor(type, color)
       ..borderRadius = edges[type]
       ..shape = type == MaterialType.circle ? Shape.circle : Shape.rectangle;
     watchPerformance(_builder.createPerformance(
-        [_builder.shadow], duration: _kAnimateShadowDuration));
+        [_builder.shadow],
+        duration: _kAnimateShadowDuration
+    ));
     watchPerformance(_builder.createPerformance(
-        [_builder.backgroundColor], duration: _kAnimateColorDuration));
+        [_builder.backgroundColor],
+        duration: _kAnimateColorDuration
+    ));
     super.initState();
   }
 
   void syncFields(Material source) {
     child = source.child;
     type = source.type;
     level = source.level;
     color = source.color;
     _builder.updateFields(
       shadow: new AnimatedType<double>(level.toDouble()),
@@ skipping 20 matching lines @@
     return color == null ? null : new AnimatedColor(color);
   }
 
   Widget build() {
     return _builder.build(
         new DefaultTextStyle(style: Theme.of(this).text.body1, child: child)
     );
   }
 
 }