Implement (subset of) ISO 8601 for date-reading. Fix other bugs.

tests/corelib/src/DateTimeTest.dart

 // Copyright (c) 2011, 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 Date.
 
 class DateTest {
   // Tests if the time moves eventually forward.
   static void testNow() {
     var t1 = new Date.now();
@@ skipping 305 matching lines @@
     var dt3 = dt2.subtract(new Duration(milliseconds:
         3 * Duration.MILLISECONDS_PER_SECOND + 5));
     Expect.equals(true, dt1 == dt3);
     Expect.equals(false, dt1 == dt2);
   }
 
   static void testDateStrings() {
     // TODO(floitsch): Clean up the Date API that deals with strings.
     var dt1 = new Date.fromString("2011-05-11 18:58:35Z");
     Expect.equals(1305140315000, dt1.value);
+    Expect.isTrue(dt1.isUtc());
     var str = dt1.toString();
     var dt2 = new Date.fromString(str);
     Expect.equals(true, dt1 == dt2);
     var dt3 = dt1.changeTimeZone(const TimeZone.utc());
     str = dt3.toString();
     Expect.equals("2011-05-11 18:58:35.000Z", str);
   }
 
   static void testWeekday() {
     // 2011-10-06 is Summertime.
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     testDateStrings();
     testEquivalentYears();
     testFarAwayDates();
     testWeekday();
   }
 }
 
 main() {
   DateTest.testMain();
 }