Clean up a bunch of our Dart code.

sky/engine/core/painting/Color.dart

Index: sky/engine/core/painting/Color.dart
diff --git a/sky/engine/core/painting/Color.dart b/sky/engine/core/painting/Color.dart
index be59871bb10ddd626dfe78d8cc75368fac25c20f..65ed9be1db6cabc6fce24b5d471c2dc9def783db 100644
--- a/sky/engine/core/painting/Color.dart
+++ b/sky/engine/core/painting/Color.dart
@@ -5,9 +5,6 @@
 part of dart.sky;
 
 class Color {
-  final int _value;
-  int get value => _value;
-
   const Color(this._value);
   const Color.fromARGB(int a, int r, int g, int b) :
     _value = (((a & 0xff) << 24) |
@@ -15,6 +12,9 @@ class Color {
               ((g & 0xff) << 8) |
               ((b & 0xff) << 0));
 
+  final int _value;
+  int get value => _value;
+
   int get alpha => (0xff000000 & _value) >> 24;
   int get red => (0x00ff0000 & _value) >> 16;
   int get green => (0x0000ff00 & _value) >> 8;