Change Rectangle.operator== to compare right/bottom instead of width/height.

sdk/lib/math/rectangle.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. 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.math;
 
 /**
  * A base class for representing two-dimensional axis-aligned rectangles.
  *
  * This rectangle uses a left-handed Cartesian coordinate system, with x
  * directed to the right and y directed down, as per the convention in 2D
@@ skipping 18 matching lines @@
   T get right => left + width;
   /** The y-coordinate of the bottom edge. */
   T get bottom => top + height;
 
   String toString() {
     return 'Rectangle ($left, $top) $width x $height';
   }
 
   bool operator ==(other) {
     if (other is !Rectangle) return false;
-    return left == other.left && top == other.top && width == other.width &&
-        height == other.height;
+    return left == other.left && top == other.top && right == other.right &&
+        bottom == other.bottom;
   }
 
   int get hashCode => _JenkinsSmiHash.hash4(left.hashCode, top.hashCode,
-      width.hashCode, height.hashCode);
+      right.hashCode, bottom.hashCode);
 
   /**
    * Computes the intersection of `this` and [other].
    *
    * The intersection of two axis-aligned rectangles, if any, is always another
    * axis-aligned rectangle.
    *
    * Returns the intersection of this and `other`, or `null` if they don't
    * intersect.
    */
@@ skipping 100 matching lines @@
   MutableRectangle(this.left, this.top, this.width, this.height);
 
   factory MutableRectangle.fromPoints(Point<T> a, Point<T> b) {
     T left = min(a.x, b.x);
     T width = max(a.x, b.x) - left;
     T top = min(a.y, b.y);
     T height = max(a.y, b.y) - top;
     return new MutableRectangle<T>(left, top, width, height);
   }
 }