Roll Observatory packages and add a roll script

packages/analyzer/lib/src/generated/incremental_resolution_validator.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.
 
 library engine.incremental_resolution_validator;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 
 /**
@@ skipping 918 matching lines @@
    *     package:project/my_lib.dart      -> my_lib.dart
    */
   static String _getShortElementLocationUri(String uri) {
     int index = uri.lastIndexOf('/');
     if (index == -1) {
       return uri;
     }
     return uri.substring(index + 1);
   }
 }