Roll Observatory packages and add a roll script

packages/dart_style/lib/src/io.dart

 // Copyright (c) 2014, 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 dart_style.src.io;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 
@@ skipping 54 matching lines @@
     stderr.writeln(err.message(color: color));
   } catch (err, stack) {
     stderr.writeln('''Hit a bug in the formatter when formatting $label.
 Please report at: github.com/dart-lang/dart_style/issues
 $err
 $stack''');
   }
 
   return false;
 }