Make hashCode a getter and not a method.

pkg/fixnum/int64.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.
 
 /**
  * An immutable 64-bit signed integer, in the range [-2^63, 2^63 - 1].
  * Arithmetic operations may overflow in order to maintain this range.
  */
 class int64 implements intx {
 
@@ skipping 553 matching lines @@
   bool isEven() => (_l & 0x1) == 0;
   bool isMaxValue() => (_h == _MASK_2 >> 1) && _m == _MASK && _l == _MASK;
   bool isMinValue() => _h == _SIGN_BIT_VALUE && _m == 0 && _l == 0;
   bool isNegative() => (_h >> (_BITS2 - 1)) != 0;
   bool isOdd() => (_l & 0x1) == 1;
   bool isZero() => _h == 0 && _m == 0 && _l == 0;
 
   /**
    * Returns a hash code based on all the bits of this [int64].
    */
-  int hashCode() {
+  int get hashCode {
     int bottom = ((_m & 0x3ff) << _BITS) | _l;
     int top = (_h << 12) | ((_m >> 10) & 0xfff);
     return bottom ^ top;
   }
 
   int64 abs() {
     return this < 0 ? -this : this;
   }
 
   /**
@@ skipping 501 matching lines @@
         }
       }
       return ZERO;
     }
 
     // Generate the quotient using bit-at-a-time long division.
     return _divModHelper(aIsCopy ? a : new int64._copy(a), b, negative,
         aIsNegative, aIsMinValue, computeRemainder);
   }
 }