Roll Observatory packages and add a roll script

packages/stack_trace/lib/src/vm_trace.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 vm_trace;
 
 import 'frame.dart';
 import 'utils.dart';
 
 /// An implementation of [StackTrace] that emulates the behavior of the VM's
@@ skipping 14 matching lines @@
       var member = frame.member
           .replaceAllMapped(new RegExp(r"[^.]+\.<async>"),
               (match) => "${match[1]}.<${match[1]}_async_body>")
           .replaceAll("<fn>", "<anonymous closure>");
       var line = frame.line == null ? 0 : frame.line;
       var column = frame.column == null ? 0 : frame.column;
       return "$number$member (${frame.uri}:$line:$column)\n";
     }).join();
   }
 }