Update ink splash to new animation system

sky/sdk/lib/animation/animation_performance.dart

Index: sky/sdk/lib/animation/animation_performance.dart
diff --git a/sky/sdk/lib/animation/animation_performance.dart b/sky/sdk/lib/animation/animation_performance.dart
index 829f9e55ad8ddba46d3df9965d73bc4e0923db21..d6d9edc1f8fc268c630c6fd64fb9fab5f85b5bf4 100644
--- a/sky/sdk/lib/animation/animation_performance.dart
+++ b/sky/sdk/lib/animation/animation_performance.dart
@@ -12,14 +12,15 @@ abstract class AnimatedVariable {
 }
 
 class AnimatedType<T extends dynamic> extends AnimatedVariable {
-  T value;
-  T begin, end;
-  final Curve curve;
-
   AnimatedType(this.begin, {this.end, this.curve: linear}) {
     value = begin;
   }
 
+  T value;
+  T begin;
+  T end;
+  Curve curve;
+
   void setFraction(double t) {
     if (end != null) {
       // TODO(mpcomplete): Reverse the timeline and curve.