Remove _BufferList from dart:io and now use BytesBuilder.

runtime/bin/process_patch.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.
 
 patch class _WindowsCodePageDecoder {
   /* patch */ static String _decodeBytes(List<int> bytes)
       native "SystemEncodingToString";
 }
 
 
@@ skipping 341 matching lines @@
                        runInShell: runInShell).then((Process p) {
     int pid = p.pid;
 
     // Make sure the process stdin is closed.
     p.stdin.close();
 
     // Setup stdout and stderr handling.
     Future foldStream(Stream<List<int>> stream, Encoding encoding) {
       if (encoding == null) {
         return stream
-            .fold(
-                new _BufferList(),
-                (buf, data) {
-                  buf.add(data);
-                  return buf;
-                })
-            .then((buf) => buf.readBytes());
+            .fold(new BytesBuilder(), (builder, data) => builder..add(data))
+            .then((builder) => builder.takeBytes());
       } else {
         return stream
             .transform(new StringDecoder(encoding))
             .fold(
                 new StringBuffer(),
                 (buf, data) {
                   buf.write(data);
                   return buf;
                 })
             .then((sb) => sb.toString());
@@ skipping 14 matching lines @@
   const _ProcessResult(int this.pid,
                        int this.exitCode,
                        this.stdout,
                        this.stderr);
 
   final int pid;
   final int exitCode;
   final stdout;
   final stderr;
 }