Roll Observatory packages and add a roll script

packages/matcher/lib/mirror_matchers.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.
 
 /// The mirror matchers library provides some additional matchers that
 /// make use of `dart:mirrors`.
 library matcher.mirror_matchers;
 
 import 'dart:mirrors';
 
@@ skipping 59 matching lines @@
       var innerDescription = new StringDescription();
       _matcher.describeMismatch(
           matchState['value'], innerDescription, matchState['state'], verbose);
       if (innerDescription.length > 0) {
         mismatchDescription.add(' which ').add(innerDescription.toString());
       }
     }
     return mismatchDescription;
   }
 }