Roll Observatory packages and add a roll script

packages/stack_trace/lib/src/stack_zone_specification.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 stack_trace.stack_zone_specification;
 
 import 'dart:async';
 
 import 'trace.dart';
 import 'chain.dart';
@@ skipping 216 matching lines @@
   Chain toChain() {
     var nodes = <Trace>[];
     var node = this;
     while (node != null) {
       nodes.add(node.trace);
       node = node.previous;
     }
     return new Chain(nodes);
   }
 }