Trivial code style changes in animation code.

R=mpcomplete@chromium.org

Review URL: https://codereview.chromium.org/1232403004 .

sdk/lib/animation/animation_performance.dart

@@ -7,10 +7,11 @@ import 'package:sky/animation/curves.dart';
 
 abstract class AnimatedVariable {
   void setFraction(double t);
+  String toString();
 }
 
 class AnimatedType<T extends dynamic> extends AnimatedVariable {
-  AnimatedType(this.begin, {this.end, this.curve: linear}) {
+  AnimatedType(this.begin, { this.end, this.curve: linear }) {
     value = begin;
   }
 
@@ -25,6 +26,8 @@ class AnimatedType<T extends dynamic> extends AnimatedVariable {
       value = begin + (end - begin) * curve.transform(t);
     }
   }
+
+  String toString() => 'AnimatedType(begin=$begin, end=$end, value=$value)';
 }
 
 class AnimatedList extends AnimatedVariable {
@@ -34,6 +37,7 @@ class AnimatedList extends AnimatedVariable {
     for (AnimatedVariable variable in variables)
       variable.setFraction(t);
   }
+  String toString() => 'AnimatedList([$variables])';
 }
 
 // This class manages a "performance" - a collection of values that change

sdk/lib/widgets/animation_builder.dart

@@ -15,6 +15,9 @@ import 'package:sky/widgets/basic.dart';
 // animated properties. Use syncFields to update the Container's properties,
 // which will optionally animate them using an AnimationPerformance.
 class AnimationBuilder {
+
+  AnimationBuilder();
+
   AnimatedType<double> opacity;
   AnimatedType<Point> position;
   AnimatedType<double> shadow;
@@ -27,10 +30,8 @@ class AnimationBuilder {
   Map<AnimatedVariable, AnimationPerformance> _variableToPerformance =
       new Map<AnimatedVariable, AnimationPerformance>();
 
-  AnimationBuilder();
-
   AnimationPerformance createPerformance(List<AnimatedType> variables,
-                                         {Duration duration}) {
+                                         { Duration duration }) {
     AnimationPerformance performance = new AnimationPerformance()
       ..duration = duration
       ..variable = new AnimatedList(variables);
@@ -65,10 +66,12 @@ class AnimationBuilder {
     return current;
   }
 
-  void updateFields({ AnimatedType<double> shadow,
-                      AnimatedColor backgroundColor,
-                      double borderRadius,
-                      Shape shape }) {
+  void updateFields({
+    AnimatedType<double> shadow,
+    AnimatedColor backgroundColor,
+    double borderRadius,
+    Shape shape
+  }) {
     _updateField(this.shadow, shadow);
     _updateField(this.backgroundColor, backgroundColor);
     this.borderRadius = borderRadius;
@@ -77,7 +80,7 @@ class AnimationBuilder {
 
   void _updateField(AnimatedType variable, AnimatedType sourceVariable) {
     if (variable == null)
-      return;  // TODO(mpcomplete): Should we handle transition from null?
+      return; // TODO(mpcomplete): Should we handle transition from null?
 
     AnimationPerformance performance = _variableToPerformance[variable];
     if (performance == null) {
@@ -99,8 +102,8 @@ class AnimationBuilder {
 }
 
 class AnimatedColor extends AnimatedType<Color> {
-  AnimatedColor(Color begin, {Color end, Curve curve: linear})
-      : super(begin, end: end, curve: curve);
+  AnimatedColor(Color begin, { Color end, Curve curve: linear })
+    : super(begin, end: end, curve: curve);
 
   void setFraction(double t) {
     value = lerpColor(begin, end, t);

sdk/lib/widgets/material.dart

@@ -39,18 +39,22 @@ class Material extends AnimatedComponent {
   int level;
   Color color;
 
-  AnimationBuilder _builder;
+  final AnimationBuilder _builder = new AnimationBuilder();
 
   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();
   }