Remove _BufferList from dart:io and now use BytesBuilder.

sdk/lib/io/http_headers.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.
 
 part of dart.io;
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders(String this.protocolVersion)
       : _headers = new Map<String, List<String>>();
 
@@ skipping 326 matching lines @@
         protocolVersion == "1.1") {
       contentLength = -1;
     }
   }
 
   void _finalize() {
     _synchronize();
     _mutable = false;
   }
 
-  _write(_BufferList buffer) {
+  _write(BytesBuilder builder) {
     final COLONSP = const [_CharCode.COLON, _CharCode.SP];
     final COMMASP = const [_CharCode.COMMA, _CharCode.SP];
     final CRLF = const [_CharCode.CR, _CharCode.LF];
 
     // Format headers.
     _headers.forEach((String name, List<String> values) {
       bool fold = _foldHeader(name);
       var nameData = name.codeUnits;
-      buffer.add(nameData);
-      buffer.add(const [_CharCode.COLON, _CharCode.SP]);
+      builder.add(nameData);
+      builder.add(const [_CharCode.COLON, _CharCode.SP]);
       for (int i = 0; i < values.length; i++) {
         if (i > 0) {
           if (fold) {
-            buffer.add(const [_CharCode.COMMA, _CharCode.SP]);
+            builder.add(const [_CharCode.COMMA, _CharCode.SP]);
           } else {
-            buffer.add(const [_CharCode.CR, _CharCode.LF]);
-            buffer.add(nameData);
-            buffer.add(const [_CharCode.COLON, _CharCode.SP]);
+            builder.add(const [_CharCode.CR, _CharCode.LF]);
+            builder.add(nameData);
+            builder.add(const [_CharCode.COLON, _CharCode.SP]);
           }
         }
-        buffer.add(values[i].codeUnits);
+        builder.add(values[i].codeUnits);
       }
-      buffer.add(const [_CharCode.CR, _CharCode.LF]);
+      builder.add(const [_CharCode.CR, _CharCode.LF]);
     });
   }
 
   String toString() {
     StringBuffer sb = new StringBuffer();
     _headers.forEach((String name, List<String> values) {
       sb.write(name);
       sb.write(": ");
       bool fold = _foldHeader(name);
       for (int i = 0; i < values.length; i++) {
@@ skipping 390 matching lines @@
 
   String name;
   String value;
   DateTime expires;
   int maxAge;
   String domain;
   String path;
   bool httpOnly = false;
   bool secure = false;
 }