Deprecate comparison operators of DateTime.

tests/corelib/date_time_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.
 
 // Dart test program for DateTime.
 
 class DateTest {
   // Tests if the time moves eventually forward.
   static void testNow() {
     var t1 = new DateTime.now();
@@ skipping 299 matching lines @@
     Expect.equals(true,
                   (dt1.minute == dt2.minute) ||
                   ((dt1.minute - dt2.minute).abs() == 30) ||
                   ((dt1.minute - dt2.minute).abs() == 15));
     Expect.equals(dt1.second, dt2.second);
     Expect.equals(dt1.millisecond, dt2.millisecond);
   }
 
   static void testConstructors() {
     var dt0 = new DateTime.utc(2011, 5, 11, 18, 58, 35, 0);
+    var dt0b = new DateTime.utc(2011, 5, 11, 18, 58, 35, 0).toLocal();
     Expect.equals(1305140315000, dt0.millisecondsSinceEpoch);
     var dt1 = new DateTime.fromMillisecondsSinceEpoch(1305140315000);
     Expect.equals(dt1.millisecondsSinceEpoch, dt0.millisecondsSinceEpoch);
-    Expect.equals(true, dt1 == dt0);
+    Expect.equals(false, dt1 == dt0);
+    Expect.equals(true, dt1 == dt0b);
     var dt3 = new DateTime(dt1.year, dt1.month, dt1.day, dt1.hour, dt1.minute,
                        dt1.second, dt1.millisecond);
     Expect.equals(dt1.millisecondsSinceEpoch, dt3.millisecondsSinceEpoch);
+    Expect.equals(false, dt3 == dt0);
     Expect.equals(true, dt1 == dt3);
     dt3 = new DateTime(
         dt1.year, dt1.month, dt1.day, dt1.hour, dt1.minute,
         dt1.second, dt1.millisecond);
     Expect.equals(dt1.millisecondsSinceEpoch, dt3.millisecondsSinceEpoch);
     Expect.equals(true, dt1 == dt3);
     var dt2 = dt1.toLocal();
     dt3 = new DateTime(2011, 5, dt1.day, dt1.hour, dt1.minute, 35, 0);
     Expect.equals(dt2.millisecondsSinceEpoch, dt3.millisecondsSinceEpoch);
     Expect.equals(true, dt2 == dt3);
@@ skipping 481 matching lines @@
     testEquivalentYears();
     testExtremes();
     testFarAwayDates();
     testWeekday();
   }
 }
 
 main() {
   DateTest.testMain();
 }