Move pub into sdk/lib/_internal.

sdk/lib/_internal/pub/lib/src/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 'package:pathos/path.dart' as path;
@@ skipping 79 matching lines @@
       builder
         ..write(source.substring(lastMatchEnd, match.start + 1))
         ..write("_")
         ..write(match.group(1).toLowerCase());
       lastMatchEnd = match.end;
     }
     builder.write(source.substring(lastMatchEnd));
     return builder.toString().toLowerCase();
   }
 }