Roll Observatory packages and add a roll script

packages/charted/lib/locale/format/time_format.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.locale.format;
 
 typedef String TimeFormatFunction(DateTime date);
@@ skipping 116 matching lines @@
 
   UTCTimeFormat _getInstance(String template) {
     return new UTCTimeFormat(template, _locale);
   }
 
   DateTime parse(String string) {
     assert(_dateFormat != null);
     return _dateFormat.parseUTC(string);
   }
 }