Roll Observatory packages and add a roll script

packages/initialize/lib/src/initializer.dart

 // Copyright (c) 2015, 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.
 part of initialize;
 
 /// Implement this class to create your own initializer.
 ///
 /// Hello world example:
 ///
 ///   class Print implements Initializer<Type> {
@@ skipping 28 matching lines @@
   // The path to the library.
   final String path;
 
   const LibraryIdentifier(this.name, this.package, this.path);
 
   bool operator ==(LibraryIdentifier other) =>
       name == other.name && package == other.package && path == other.path;
 
   String toString() => '$name: $package:$path';
 }