Fix the floating action button.

sky/engine/core/painting/Rect.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.
 
 part of dart.sky;
 
 /// Holds 4 floating-point coordinates for a rectangle.
 class Rect {
   Rect();
 
@@ skipping 12 matching lines @@
       ..[2] = left + width
       ..[3] = top + height;
   }
 
   final Float32List _value = new Float32List(4);
   double get left => _value[0];
   double get top => _value[1];
   double get right => _value[2];
   double get bottom => _value[3];
 
-  Point get center => new Point(left + right / 2.0, top + bottom / 2.0);
+  double get width => right - left;
+  double get height => bottom - top;
+
+  Size get size => new Size(width, height);
+
+  double get shortestSide {
+    double w = width.abs();
+    double h = height.abs();
+    return w < h ? w : h;
+  }
+
+  Point get center => new Point(left + width / 2.0, top + height / 2.0);
   Point get topLeft => new Point(left, top);
   Point get topRight => new Point(right, top);
   Point get bottomLeft => new Point(left, bottom);
   Point get bottomRight => new Point(right, bottom);
 
-  Size get size => new Size(right - left, bottom - top);
-
   // Rects are inclusive of the top and left edges but exclusive of the bottom
   // right edges.
   bool contains(Point point) {
     return point.x >= left && point.x < right && point.y >= top && point.y < bottom;
   }
 
   bool operator ==(other) {
     if (other is! Rect)
       return false;
     for (var i = 0; i < 4; ++i) {
       if (_value[i] != other._value[i])
         return false;
     }
     return true;
   }
   int get hashCode =>_value.fold(373, (value, item) => (37 * value + item.hashCode));
   String toString() => "Rect.fromLTRB($left, $top, $right, $bottom)";
 }