Remove deprecated classes and functions in Date.

tests/standalone/io/http_headers_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");
@@ skipping 271 matching lines @@
 
   void checkCookie(cookie, s) {
     Expect.equals(s, cookie.toString());
     var c = new _Cookie.fromSetCookieValue(s);
     checkCookiesEquals(cookie, c);
   }
 
   Cookie cookie;
   cookie = new Cookie("name", "value");
   Expect.equals("name=value", cookie.toString());
-  TimeZone utc = new TimeZone.utc();
-  Date date = new Date.withTimeZone(2014, Date.JAN, 5, 23, 59, 59, 0, utc);
+  Date date = new Date(2014, Date.JAN, 5, 23, 59, 59, 0, isUtc: true);
   cookie.expires = date;
   checkCookie(cookie, "name=value"
                       "; Expires=Sun, 5 Jan 2014 23:59:59 GMT");
   cookie.maxAge = 567;
   checkCookie(cookie, "name=value"
                       "; Expires=Sun, 5 Jan 2014 23:59:59 GMT"
                       "; Max-Age=567");
   cookie.domain = "example.com";
   checkCookie(cookie, "name=value"
                       "; Expires=Sun, 5 Jan 2014 23:59:59 GMT"
@@ skipping 61 matching lines @@
   testMultiValue();
   testExpires();
   testHost();
   testEnumeration();
   testHeaderValue();
   testContentType();
   testContentTypeCache();
   testCookie();
   testInvalidCookie();
 }