Use Point, Size, and Rect in layout2.dart

sky/engine/core/painting/Point.dart

Index: sky/engine/core/painting/Point.dart
diff --git a/sky/engine/core/painting/Point.dart b/sky/engine/core/painting/Point.dart
index 82d2875e3b82c72a145429c439229f2d92c3839d..ad0dbbb74e7ec2e940e91a75aecf53b65d68bfdb 100644
--- a/sky/engine/core/painting/Point.dart
+++ b/sky/engine/core/painting/Point.dart
@@ -9,7 +9,7 @@ class Point {
   double x;
   double y;
 
-  Point(this.x, this.y);
+  Point([this.x = 0.0, this.y = 0.0]);

[Hixie, 2015/05/28 18:45:21]

I think we should make these required. These don't really convey what they mean:

  new Point();
  new Point(5.0);

 
   bool operator ==(other) {
     if (!(other is Point)) return false;