Don't test writing 1 byte 65k times.

tests/standalone/io/process_sync_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 "dart:io";
 
 test(int blockCount,
      int stdoutBlockSize,
@@ skipping 32 matching lines @@
   test(10, 100, 10, 0);
   test(10, 10, 100, 0);
   test(100, 1, 10, 0);
   test(100, 10, 1, 0);
   test(100, 1, 1, 0);
   test(1, 100000, 100000, 0);
 
   // The buffer size used in process.h.
   var kBufferSize = 16 * 1024;
   test(1, kBufferSize, kBufferSize, 0);
-  test(1, kBufferSize - 1, kBufferSize + 1, 0);
-  test(kBufferSize - 1, 1, 1, 0);
-  test(kBufferSize, 1, 1, 0);
-  test(kBufferSize + 1, 1, 1, 0);
+  test(1, kBufferSize - 1, kBufferSize - 1, 0);
+  test(1, kBufferSize + 1, kBufferSize + 1, 0);
 
   test(10, 10, 10, 1);
   test(10, 10, 10, 255);
   test(10, 10, 10, -1, 255);
   test(10, 10, 10, -255, 1);
 }