Make hashCode a getter and not a method.

pkg/fixnum/intx.dart

 // Copyright (c) 2012, 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 fixed-precision integer.
  */
 abstract class intx implements Comparable {
 
   // Arithmetic operations.
@@ skipping 28 matching lines @@
   bool operator >=(other);
 
   // Testers.
   bool isEven();
   bool isMaxValue();
   bool isMinValue();
   bool isNegative();
   bool isOdd();
   bool isZero();
 
-  int hashCode();
+  int get hashCode;
 
   intx abs();
 
   /**
    * Returns the number of leading zeros in this [intx] as an [int]
    * between 0 and 64.
    */
   int numberOfLeadingZeros();
 
   /**
@@ skipping 34 matching lines @@
    * Returns the value of this [intx] as a hexadecimal [String].
    */
   String toHexString();
 
   /**
    * Returns the value of this [intx] as a [String] in the given radix.
    * [radix] must be an integer between 2 and 16, inclusive.
    */
   String toRadixString(int radix);
 }