Roll Observatory packages and add a roll script

packages/charted/lib/core/utils/namespace.dart

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //
 
 part of charted.core.utils;
 
@@ skipping 45 matching lines @@
       localName = tagName.substring(separatorIdx + 1);
     }
 
     if (NS_PREFIXES.containsKey(prefix)) {
       namespaceUri = NS_PREFIXES[prefix];
     } else {
       localName = tagName;
     }
   }
 }