Make Comparable generic.

pkg/fixnum/lib/src/int32.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.
 
 part of fixnum;
 
 /**
  * An immutable 32-bit signed integer, in the range [-2^31, 2^31 - 1].
  * Arithmetic operations may overflow in order to maintain this range.
  */
@@ skipping 270 matching lines @@
   bool operator ==(other) {
     if (other == null) {
       return false;
     }
     if (other is int64) {
       return this.toInt64() == other;
     }
     return _i == _convert(other);
   }
 
-  int compareTo(Comparable other) {
+  int compareTo(other) {
     if (other is int64) {
       return this.toInt64().compareTo(other);
     }
     return _i.compareTo(_convert(other));
   }
 
   bool operator <(other) {
     if (other is int64) {
       return this.toInt64() < other;
     }
@@ skipping 45 matching lines @@
   }
 
   int toInt() => _i;
   int32 toInt32() => this;
   int64 toInt64() => new int64.fromInt(_i);
 
   String toString() => _i.toString();
   String toHexString() => _i.toRadixString(16);
   String toRadixString(int radix) => _i.toRadixString(radix);
 }