Deprecate use of timezones.

runtime/bin/http_utils.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.
 
 class _HttpUtils {
   static String decodeUrlEncodedString(String urlEncoded) {
     // First check the string for any encoding.
     int index = 0;
     bool encoded = false;
     while (!encoded && index < urlEncoded.length) {
@@ skipping 80 matching lines @@
   // month        = "Jan" | "Feb" | "Mar" | "Apr"
   //              | "May" | "Jun" | "Jul" | "Aug"
   //              | "Sep" | "Oct" | "Nov" | "Dec"
 
   // Format as RFC 1123 date.
   static String formatDate(Date date) {
     List wkday = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"];
     List month = ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
                   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
 
-    Date d = date.changeTimeZone(new TimeZone.utc());
+    Date d = date.toUtc();
     StringBuffer sb = new StringBuffer();
     sb.add(wkday[d.weekday]);
     sb.add(", ");
     sb.add(d.day.toString());
     sb.add(" ");
     sb.add(month[d.month - 1]);
     sb.add(" ");
     sb.add(d.year.toString());
     d.hours < 9 ? sb.add(" 0") : sb.add(" ");
     sb.add(d.hours.toString());
@@ skipping 115 matching lines @@
       expect(" ");
       day = expectNum(format == formatRfc1123 ? " " : "-");
       month = expectMonth(format == formatRfc1123 ? " " : "-");
       year = expectNum(" ");
       hours = expectNum(":");
       minutes = expectNum(":");
       seconds = expectNum(" ");
       expect("GMT");
     }
     expectEnd();
-    TimeZone utc = new TimeZone.utc();
-    return new Date.withTimeZone(
-        year, month + 1, day, hours, minutes, seconds, 0, utc);
+    return new Date(
+        year, month + 1, day, hours, minutes, seconds, 0, isUtc: true);
   }
 }