Roll Observatory packages and add a roll script

packages/utf/lib/src/util.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 utf.util;
 
 import 'constants.dart';
 import 'list_range.dart';
 import 'utf_16_code_unit_decoder.dart';
 
@@ skipping 58 matching lines @@
       codeUnitsBuffer[j++] = UNICODE_UTF16_SURROGATE_UNIT_1_BASE +
           (base & UNICODE_UTF16_LO_MASK);
     } else if (replacementCodepoint != null) {
       codeUnitsBuffer[j++] = replacementCodepoint;
     } else {
       throw new ArgumentError("Invalid encoding");
     }
   }
   return codeUnitsBuffer;
 }