Make isEmpty a getter.

samples/ui_lib/base/Size.dart

 // Copyright (c) 2011, 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.
 
 /**
  * A utility class for representing two-dimensional sizes.
  */
 class Size {
   num width;
   num height;
@@ skipping 65 matching lines @@
    * Returns the shorter of the two dimensions in the size.
    */
   num getShortest() {
     return min(width, height);
   }
 
   /**
    * Returns true if the size has zero area, false if both dimensions
    *     are non-zero numbers.
    */
-  bool isEmpty() {
+  bool get isEmpty {
     return area() == 0;
   }
 
   /**
    * Returns the perimeter of the size (width + height) * 2.
    */
   num perimeter() {
     return (width + height) * 2;
   }
 
@@ skipping 32 matching lines @@
   }
 
   /**
    * Returns a nice string representing size.
    * Returns in the form (50 x 73).
    */
   String toString() {
     return "(${width} x ${height})";
   }
 }