Fix zlib test on Windows.

tests/standalone/io/zlib_test.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
 void testZLibDeflate() {
   test(int level, List<int> expected) {
@@ skipping 40 matching lines @@
 void testZLibDeflateGZip() {
   var port = new ReceivePort();
   var data = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
   var controller = new StreamController();
   controller.stream.transform(new ZLibDeflater())
       .reduce([], (buffer, data) {
         buffer.addAll(data);
         return buffer;
       })
       .then((data) {
-        Expect.listEquals([31, 139, 8, 0, 0, 0, 0, 0, 0, 3, 98, 96, 100, 98,
-                           102, 97, 101, 99, 231, 224, 4, 0, 0, 0, 255, 255],
-                          data);
+        Expect.equals(26, data.length);
+        Expect.listEquals([98, 96, 100, 98, 102, 97, 101, 99, 231, 224, 4, 0, 0,
+                           0, 255, 255],
+                          // Skip header, as it can change.
+                          data.getRange(10, 16));
         port.close();
       });
   controller.add(data);
   controller.close();
 }
 
 void testZLibDeflateInvalidLevel() {
   test2(gzip, level) {
     var port = new ReceivePort();
     try {
@@ skipping 42 matching lines @@
     test(i);
   }
 }
 
 void main() {
   testZLibDeflate();
   testZLibDeflateGZip();
   testZLibDeflateInvalidLevel();
   testZLibInflate();
 }