Use less data for regression_21160_test to eliminate simulator timeouts

dart/tests/standalone/io/regress_21160_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 "package:expect/expect.dart";
 import "package:path/path.dart";
 import "package:async_helper/async_helper.dart";
 
 import "dart:async";
 import "dart:io";
 import "dart:typed_data";
 
-// 1 MB of i%256 data.
+// 10 KiB of i%256 data.
 Uint8List DATA = new Uint8List.fromList(
-    new List.generate(1024 * 1024, (i) => i % 256));
+    new List.generate(10 * 1024, (i) => i % 256));
 
 Future<SecureServerSocket> startServer() {
   return SecureServerSocket.bind("localhost",
                                  0,
                                  'localhost_cert').then((server) {
     server.listen((SecureSocket request) {
       request.drain().then((_) {
         request
             ..add(DATA)
             ..close();
@@ skipping 44 matching lines @@
             Expect.equals(body.length, DATA.length);
             for (int i = 0; i < body.length; i++) {
               Expect.equals(body[i], DATA[i]);
             }
             server.close();
             asyncEnd();
           });
     });
   });
 }