Fix test tests/standalone/io/http_headers_test

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 214 matching lines @@
   Expect.equals("text/html", contentType.value);
 
   contentType = new _ContentType.fromString("text/html");
   check(contentType, "text", "html");
   Expect.equals("text/html", contentType.toString());
   contentType.parameters["charset"] = "utf-8";
   check(contentType, "text", "html", {"charset": "utf-8"});
   Expect.equals("text/html; charset=utf-8", contentType.toString());
   contentType.parameters["xxx"] = "yyy";
   check(contentType, "text", "html", {"charset": "utf-8", "xxx": "yyy"});
-  Expect.equals("text/html; charset=utf-8; xxx=yyy", contentType.toString());
+  String s = contentType.toString();
+  bool expectedToString = (s == "text/html; charset=utf-8; xxx=yyy" ||
+                           s == "text/html; xxx=yyy; charset=utf-8");
+  Expect.isTrue(expectedToString);
 
   contentType = new _ContentType.fromString("text/html");
   check(contentType, "text", "html");
   contentType = new _ContentType.fromString(" text/html  ");
   check(contentType, "text", "html");
   contentType = new _ContentType.fromString("text/html; charset=utf-8");
   check(contentType, "text", "html", {"charset": "utf-8"});
   contentType = new _ContentType.fromString(
       "  text/html  ;  charset  =  utf-8  ");
   check(contentType, "text", "html", {"charset": "utf-8"});
@@ skipping 29 matching lines @@
 
 main() {
   testMultiValue();
   testExpires();
   testHost();
   testEnumeration();
   testHeaderValue();
   testContentType();
   testContentTypeCache();
 }