Fix file-system-entity watching on Windows.

runtime/bin/file_patch.dart

 // Copyright (c) 2012, 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.
 
 patch class _File {
   /* patch */ static _exists(String path) native "File_Exists";
   /* patch */ static _create(String path) native "File_Create";
   /* patch */ static _createLink(String path, String target)
       native "File_CreateLink";
   /* patch */ static _linkTarget(String path) native "File_LinkTarget";
@@ skipping 74 matching lines @@
           var path = _path;
           if (event[2] != null) {
             path += Platform.pathSeparator;
             path += event[2];
           }
           return path;
         }
         bool getIsDir(event) {
           if (Platform.isWindows) {
             // Windows does not get 'isDir' as part of the event.
-            return FileSystemEntity.isDirectorySync(path);
+            return FileSystemEntity.isDirectorySync(getPath(event));
           }
           return (event[0] & FileSystemEvent._IS_DIR) != 0;
         }
         void add(event) {
           if ((event.type & _events) == 0) return;
           events.add(event);
         }
         void rewriteMove(event, isDir) {
           if (event[3]) {
             add(new FileSystemCreateEvent._(getPath(event), isDir));
@@ skipping 67 matching lines @@
 
   int _watchPath(String path, int events, bool recursive)
       native "FileSystemWatcher_WatchPath";
   void _unwatchPath() native "FileSystemWatcher_UnwatchPath";
   List _readEvents() native "FileSystemWatcher_ReadEvents";
 }
 
 Uint8List _makeUint8ListView(Uint8List source, int offsetInBytes, int length) {
   return new Uint8List.view(source.buffer, offsetInBytes, length);
 }