Roll Observatory packages and add a roll script

packages/path/lib/src/style/windows.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.
 
 library path.style.windows;
 
 import '../characters.dart' as chars;
 import '../internal_style.dart';
 import '../parsed_path.dart';
 import '../utils.dart';
@@ skipping 105 matching lines @@
 
       // Get rid of the trailing "\" in "C:\" because the URI constructor will
       // add a separator on its own.
       parsed.parts.insert(
           0, parsed.root.replaceAll("/", "").replaceAll("\\", ""));
 
       return new Uri(scheme: 'file', pathSegments: parsed.parts);
     }
   }
 }