Fix date_time_test to not assume a particular slowness of running code.

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.
 
 import "package:expect/expect.dart";
 
 // Dart test program for DateTime.
 
 // Identical to _MAX_MILLISECONDS_SINCE_EPOCH in date_time.dart
 const int _MAX_MILLISECONDS = 8640000000000000;
 
 // Tests if the time moves eventually forward.
 void testNow() {
   var t1 = new DateTime.now();
   bool timeMovedForward = false;
-  for (int i = 0; i < 1000000; i++) {
+  while (true) {
     var t2 = new DateTime.now();

[ricow1, 2014/12/03 06:55:46]

I would add a count, and print to stdout for every 1,000,000 iterations, that
way we actually know that we are waiting here if the test should time out,
something like:
print("Still waiting for time to move forward: t1 was
${t1.millisecondsSinceEpoch}, t2 was {t2.millisecondsSinceEpoch}, did $count
calls to DateTime.now()")

[Lasse Reichstein Nielsen, 2014/12/03 07:14:47]

Done.

     if (t1.millisecondsSinceEpoch < t2.millisecondsSinceEpoch) {
-      timeMovedForward = true;
       break;
     }
   }
-  Expect.equals(true, timeMovedForward);
   Expect.isFalse(t1.isUtc);
 }
 
 void testValue() {
   var dt1 = new DateTime.now();
   var millisecondsSinceEpoch = dt1.millisecondsSinceEpoch;
   var dt2 = new DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch);
   Expect.equals(millisecondsSinceEpoch, dt2.millisecondsSinceEpoch);
 }
 
@@ skipping 928 matching lines @@
   testSubAdd();
   testUnderflowAndOverflow();
   testDateStrings();
   testEquivalentYears();
   testExtremes();
   testFarAwayDates();
   testWeekday();
   testToStrings();
   testIsoString();
 }