Don't throw exception for non-integer args to fixnum int32,int64 op ==

pkg/fixnum/test/int_32_test.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.
 
 library int32test;
 import 'package:fixnum/fixnum.dart';
 import 'package:unittest/unittest.dart';
 
 void main() {
   group("arithmetic operators", () {
@@ skipping 95 matching lines @@
       expect(int32.MIN_VALUE <= int32.MAX_VALUE, true);
       expect(int32.MAX_VALUE <= int32.MIN_VALUE, false);
       expect(() => new int32.fromInt(17) <= null, throws);
     });
 
     test("==", () {
       expect(new int32.fromInt(17) == new int32.fromInt(18), false);
       expect(new int32.fromInt(17) == new int32.fromInt(17), true);
       expect(new int32.fromInt(17) == new int32.fromInt(16), false);
       expect(int32.MIN_VALUE == int32.MAX_VALUE, false);
+      expect(new int32.fromInt(17) == new Object(), false);
       expect(new int32.fromInt(17) == null, false);
     });
 
     test(">=", () {
       expect(new int32.fromInt(17) >= new int32.fromInt(18), false);
       expect(new int32.fromInt(17) >= new int32.fromInt(17), true);
       expect(new int32.fromInt(17) >= new int32.fromInt(16), true);
       expect(int32.MIN_VALUE >= int32.MAX_VALUE, false);
       expect(int32.MAX_VALUE >= int32.MIN_VALUE, true);
       expect(() => new int32.fromInt(17) >= null, throws);
@@ skipping 101 matching lines @@
           "ffffff");
     });
   });
 
   group("toRadixString", () {
     test("returns base n string representation", () {
       expect(new int32.fromInt(123456789).toRadixString(5), "223101104124");
     });
   });
 }