Deprecate use of timezones.

tests/standalone/io/http_date_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.
 
 #source("../../../runtime/bin/input_stream.dart");
 #source("../../../runtime/bin/output_stream.dart");
 #source("../../../runtime/bin/chunked_stream.dart");
 #source("../../../runtime/bin/string_stream.dart");
 #source("../../../runtime/bin/stream_util.dart");
 #source("../../../runtime/bin/http.dart");
 #source("../../../runtime/bin/http_impl.dart");
 #source("../../../runtime/bin/http_parser.dart");
 #source("../../../runtime/bin/http_utils.dart");
 
 void testParseHttpDate() {
-  TimeZone utc = new TimeZone.utc();
   Date date;
-  date = new Date.withTimeZone(1999, Date.JUN, 11, 18, 46, 53, 0, utc);
+  date = new Date(1999, Date.JUN, 11, 18, 46, 53, 0, isUtc: true);
   Expect.equals(date, _HttpUtils.parseDate("Fri, 11 Jun 1999 18:46:53 GMT"));
   Expect.equals(date, _HttpUtils.parseDate("Friday, 11-Jun-1999 18:46:53 GMT"));
   Expect.equals(date, _HttpUtils.parseDate("Fri Jun 11 18:46:53 1999"));
 
-  date = new Date.withTimeZone(1970, Date.JAN, 1, 0, 0, 0, 0, utc);
+  date = new Date(1970, Date.JAN, 1, 0, 0, 0, 0, isUtc: true);
   Expect.equals(date, _HttpUtils.parseDate("Thu, 1 Jan 1970 00:00:00 GMT"));
   Expect.equals(date,
                 _HttpUtils.parseDate("Thursday, 1-Jan-1970 00:00:00 GMT"));
   Expect.equals(date, _HttpUtils.parseDate("Thu Jan  1 00:00:00 1970"));
 
-  date = new Date.withTimeZone(2012, Date.MAR, 5, 23, 59, 59, 0, utc);
+  date = new Date(2012, Date.MAR, 5, 23, 59, 59, 0, isUtc: true);
   Expect.equals(date, _HttpUtils.parseDate("Mon, 5 Mar 2012 23:59:59 GMT"));
   Expect.equals(date, _HttpUtils.parseDate("Monday, 5-Mar-2012 23:59:59 GMT"));
   Expect.equals(date, _HttpUtils.parseDate("Mon Mar  5 23:59:59 2012"));
 }
 
 void testFormatParseHttpDate() {
   test(int year,
        int month,
        int day,
        int hours,
        int minutes,
        int seconds,
        String expectedFormatted) {
-    TimeZone utc = new TimeZone.utc();
     Date date;
     String formatted;
-    date = new Date.withTimeZone(
-        year, month, day, hours, minutes, seconds, 0, utc);
+    date = new Date(year, month, day, hours, minutes, seconds, 0, isUtc: true);
     formatted = _HttpUtils.formatDate(date);
     Expect.equals(expectedFormatted, formatted);
     Expect.equals(date, _HttpUtils.parseDate(formatted));
   }
 
   test(1999, Date.JUN, 11, 18, 46, 53, "Fri, 11 Jun 1999 18:46:53 GMT");
   test(1970, Date.JAN, 1, 0, 0, 0, "Thu, 1 Jan 1970 00:00:00 GMT");
   test(2012, Date.MAR, 5, 23, 59, 59, "Mon, 5 Mar 2012 23:59:59 GMT");
 }
 
@@ skipping 26 matching lines @@
   Expect.throws(() {
     _HttpUtils.parseDate("$valid ");
   });
 }
 
 void main() {
   testParseHttpDate();
   testFormatParseHttpDate();
   testParseHttpDateFailures();
 }