Make pub warning-clean.

utils/pub/validator/name.dart

 // Copyright (c) 2012, 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 name_validator;
 
 import 'dart:async';
 import 'dart:io';
 
 import '../../../pkg/pathos/lib/path.dart' as path;
@@ skipping 73 matching lines @@
       warnings.add('$description should be lower-case. Maybe use '
           '"${_unCamelCase(name)}"?');
     }
   }
 
   String _unCamelCase(String source) {
     var builder = new StringBuffer();
     var lastMatchEnd = 0;
     for (var match in new RegExp(r"[a-z]([A-Z])").allMatches(source)) {
       builder
-        ..add(source.substring(lastMatchEnd, match.start + 1))
-        ..add("_")
-        ..add(match.group(1).toLowerCase());
+        ..write(source.substring(lastMatchEnd, match.start + 1))
+        ..write("_")
+        ..write(match.group(1).toLowerCase());
       lastMatchEnd = match.end;
     }
-    builder.add(source.substring(lastMatchEnd));
+    builder.write(source.substring(lastMatchEnd));
     return builder.toString().toLowerCase();
   }
 }