Add microsecond support to DateTime.

tests/corelib/date_time_parse_test.dart

 // Copyright (c) 2013, 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";
 
 check(DateTime expected, String str) {
   DateTime actual = DateTime.parse(str);
   Expect.equals(expected, actual);  // Only checks if they are at the same time.
   Expect.equals(expected.isUtc, actual.isUtc);
 }
+
+bool get supportsMicroseconds =>
+    new DateTime.fromMicrosecondsSinceEpoch(1).microsecondsSinceEpoch == 1;
+
 main() {
   check(new DateTime(2012, 02, 27, 13, 27), "2012-02-27 13:27:00");
-  check(new DateTime.utc(2012, 02, 27, 13, 27, 0, 123),
-        "2012-02-27 13:27:00.123456z");
+  if (supportsMicroseconds) {
+    check(new DateTime.utc(2012, 02, 27, 13, 27, 0, 123, 456),
+          "2012-02-27 13:27:00.123456z");
+  } else {
+    check(new DateTime.utc(2012, 02, 27, 13, 27, 0, 123, 456),
+          "2012-02-27 13:27:00.123z");
+  }
   check(new DateTime(2012, 02, 27, 13, 27), "20120227 13:27:00");
   check(new DateTime(2012, 02, 27, 13, 27), "20120227T132700");
   check(new DateTime(2012, 02, 27), "20120227");
   check(new DateTime(2012, 02, 27), "+20120227");
   check(new DateTime.utc(2012, 02, 27, 14), "2012-02-27T14Z");
   check(new DateTime.utc(-12345, 1, 1), "-123450101 00:00:00 Z");
   check(new DateTime.utc(2012, 02, 27, 14), "2012-02-27T14+00");
   check(new DateTime.utc(2012, 02, 27, 14), "2012-02-27T14+0000");
   check(new DateTime.utc(2012, 02, 27, 14), "2012-02-27T14+00:00");
   check(new DateTime.utc(2012, 02, 27, 14), "2012-02-27T14 +00:00");
 
   check(new DateTime.utc(2015, 02, 14, 13, 0, 0, 0),
         "2015-02-15T00:00+11");
   check(new DateTime.utc(2015, 02, 14, 13, 0, 0, 0),
         "2015-02-15T00:00:00+11");
   check(new DateTime.utc(2015, 02, 14, 13, 0, 0, 0),
         "2015-02-15T00:00:00+11:00");
 
-  check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 501),
-        "2015-02-15T00:00:00.5005Z");
-  check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 512),
-        "2015-02-15T00:00:00.5115Z");
+  if (supportsMicroseconds) {
+    check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 500, 500),
+        "2015-02-15T00:00:00.500500Z");
+    check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 511, 500),
+        "2015-02-15T00:00:00.511500Z");
+  } else {
+    check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 501),
+        "2015-02-15T00:00:00.501Z");
+    check(new DateTime.utc(2015, 02, 15, 0, 0, 0, 512),
+        "2015-02-15T00:00:00.512Z");
+  }
 }