recompute package map when input file changes

pkg/analyzer/lib/file_system/memory_file_system.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 memory_file_system;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/engine.dart' show TimestampedData;
@@ skipping 146 matching lines @@
     _MemoryResource resource = _pathToResource[path];
     if (resource is! _MemoryFolder) {
       throw new ArgumentError(
           'Folder expected at "$path" but ${resource.runtimeType} found');
     }
   }
 
   void _notifyWatchers(String path, ChangeType changeType) {
     _pathToWatchers.forEach((String watcherPath,
         List<StreamController<WatchEvent>> streamControllers) {
-      if (posix.isWithin(watcherPath, path)) {
+      if (watcherPath == path || posix.isWithin(watcherPath, path)) {
         for (StreamController<WatchEvent> streamController
             in streamControllers) {
           streamController.add(new WatchEvent(changeType, path));
         }
       }
     });
   }
 }
 
 /**
@@ skipping 287 matching lines @@
   bool operator ==(other) {
     if (runtimeType != other.runtimeType) {
       return false;
     }
     return path == other.path;
   }
 
   @override
   String toString() => path;
 }