Add handling of the HTTP Date header

tests/standalone/src/io/HttpHeadersTest.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 31 matching lines @@
   headers.set(HttpHeaders.PRAGMA, "pragma5");
   Expect.equals(1, headers[HttpHeaders.PRAGMA].length);
 
   headers.set(HttpHeaders.PRAGMA, ["pragma6", "pragma7"]);
   Expect.equals(2, headers[HttpHeaders.PRAGMA].length);
 
   headers.removeAll(HttpHeaders.PRAGMA);
   Expect.isNull(headers[HttpHeaders.PRAGMA]);
 }
 
+void testDate() {
+  Date date1 = new Date.withTimeZone(
+      1999, Date.JUN, 11, 18, 46, 53, 0, new TimeZone.utc());
+  String httpDate1 = "Fri, 11 Jun 1999 18:46:53 GMT";
+  Date date2 = new Date.withTimeZone(
+      2000, Date.AUG, 16, 12, 34, 56, 0, new TimeZone.utc());
+  String httpDate2 = "Wed, 16 Aug 2000 12:34:56 GMT";
+
+  _HttpHeaders headers = new _HttpHeaders();
+  Expect.isNull(headers.date);
+  headers.date = date1;
+  Expect.equals(date1, headers.date);
+  Expect.equals(httpDate1, headers.value(HttpHeaders.DATE));
+  Expect.equals(1, headers[HttpHeaders.DATE].length);
+  headers.add(HttpHeaders.DATE, httpDate2);
+  Expect.equals(1, headers[HttpHeaders.DATE].length);
+  Expect.equals(date2, headers.date);
+  Expect.equals(httpDate2, headers.value(HttpHeaders.DATE));
+  headers.set(HttpHeaders.DATE, httpDate1);
+  Expect.equals(1, headers[HttpHeaders.DATE].length);
+  Expect.equals(date1, headers.date);
+  Expect.equals(httpDate1, headers.value(HttpHeaders.DATE));
+
+  headers.set(HttpHeaders.DATE, "xxx");
+  Expect.equals("xxx", headers.value(HttpHeaders.DATE));
+  Expect.equals(null, headers.date);
+}
+
 void testExpires() {
   Date date1 = new Date.withTimeZone(
       1999, Date.JUN, 11, 18, 46, 53, 0, new TimeZone.utc());
   String httpDate1 = "Fri, 11 Jun 1999 18:46:53 GMT";
   Date date2 = new Date.withTimeZone(
       2000, Date.AUG, 16, 12, 34, 56, 0, new TimeZone.utc());
   String httpDate2 = "Wed, 16 Aug 2000 12:34:56 GMT";
 
   _HttpHeaders headers = new _HttpHeaders();
   Expect.isNull(headers.expires);
@@ skipping 47 matching lines @@
   Expect.equals(":1234", headers.value(HttpHeaders.HOST));
   Expect.isNull(headers.host);
   Expect.equals(1234, headers.port);
 }
 
 main() {
   testMultiValue();
   testExpires();
   testHost();
 }