Use int for size when printing to stdout.

tests/standalone/io/print_sync_script.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:io';
 
 String get bigString {
   var buffer = new StringBuffer();
   for (var i = 0; i < 1000; i++) {
     buffer.write(i);
     for (var i = 0; i < 200; i++) {
       buffer.write('=');
     }
     buffer.writeln();
   }
   return buffer.toString();
 }
 
 main() {
-  stdout;  // Be sure too mark stdout as non-blocking.
+  stdout;  // Be sure to mark stdout as non-blocking.
   print(bigString);
 }