Remove deprecated StringBuffer.add, addAll and addCharCode.

utils/tests/peg/peg_test.dart

 // Copyright (c) 2011, 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.
 
 library peg_tests;
 import '../../peg/pegparser.dart';
 
 testParens() {
   Grammar g = new Grammar();
   Symbol a = g['A'];
@@ skipping 304 matching lines @@
   if (expected is String)
     formatted = printList(ast);
 
   Expect.equals(expected, formatted, "parse: $input");
 }
 
 // Prints the list in [1,2,3] notation, including nested lists.
 printList(item) {
   if (item is List) {
     StringBuffer sb = new StringBuffer();
-    sb.add('[');
+    sb.write('[');
     var sep = '';
     for (var x in item) {
-      sb.add(sep);
-      sb.add(printList(x));
+      sb.write(sep);
+      sb.write(printList(x));
       sep = ',';
     }
-    sb.add(']');
+    sb.write(']');
     return sb.toString();
   }
   if (item == null)
     return 'null';
   return item.toString();
 }
 
 main() {
   testCODE();
   testParens();
   testOR();
   testTEXT();
   testBlockComment();
   testC();
 }