Roll Observatory packages and add a roll script

packages/intl/lib/src/intl_message.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.
 
 /**
  * This provides classes to represent the internal structure of the
  * arguments to `Intl.message`. It is used when parsing sources to extract
  * messages or to generate code for message substitution. Normal programs
  * using Intl would not import this library.
  *
@@ skipping 747 matching lines @@
     out.write('(');
     out.write(mainArgument);
     var args = codeAttributeNames;
     out.write(", {");
     args.fold(out,
         (buffer, arg) => buffer..write("'$arg': '${this[arg].toCode()}', "));
     out.write("})}");
     return out.toString();
   }
 }