Ensure that only byte values are sent by sockets and web sockets

tests/standalone/io/raw_socket_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
@@ skipping 120 matching lines @@
 void testSimpleReadWrite() {
   // This test creates a server and a client connects. The client then
   // writes and the server echos. When the server has finished its
   // echo it half-closes. When the client gets the close event is
   // closes fully.
   ReceivePort port = new ReceivePort();
 
   const messageSize = 1000;
 
   List<int> createTestData() {
-    List<int> data = new List<int>(messageSize);
-    for (int i = 0; i < messageSize; i++) {
-      data[i] = i & 0xff;
-    }
-    return data;
+    return new List<int>.generate(messageSize, (index) => index & 0xff);
   }
 
   void verifyTestData(List<int> data) {
     Expect.equals(messageSize, data.length);
     List<int> expected = createTestData();
     for (int i = 0; i < messageSize; i++) {
       Expect.equals(expected[i], data[i]);
     }
   }
 
@@ skipping 193 matching lines @@
   testSimpleBind();
   testCloseOneEnd("client");
   testCloseOneEnd("server");
   testInvalidBind();
   testSimpleConnect();
   testServerListenAfterConnect();
   testSimpleReadWrite();
   testPauseServerSocket();
   testPauseSocket();
 }