Roll Observatory packages and add a roll script

packages/path/lib/src/internal_style.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 path.internal_style;
 
 import 'context.dart';
 import 'style.dart';
 
 /// The internal interface for the [Style] type.
@@ skipping 51 matching lines @@
 
     // Ensure that a trailing slash in the path produces a trailing slash in the
     // URL.
     if (isSeparator(path.codeUnitAt(path.length - 1))) segments.add('');
     return new Uri(pathSegments: segments);
   }
 
   /// Returns the URI that represents [path], which is assumed to be absolute.
   Uri absolutePathToUri(String path);
 }