Remove DirectoryException and LinkException from dart:io and use FileException instaed.

pkg/watcher/lib/src/utils.dart

Index: pkg/watcher/lib/src/utils.dart
diff --git a/pkg/watcher/lib/src/utils.dart b/pkg/watcher/lib/src/utils.dart
index 319835ec944f3c955db24a0006e8f9e60cb4c54b..3d00c084314ad4cfcfbb0b290f795ef56d3d3769 100644
--- a/pkg/watcher/lib/src/utils.dart
+++ b/pkg/watcher/lib/src/utils.dart
@@ -6,9 +6,10 @@ library watcher.utils;
 
 import 'dart:io';
 
-/// Returns `true` if [error] is a [DirectoryException] for a missing directory.
+/// Returns `true` if [error] is a [FileSystemException] for a missing
+/// directory.
 bool isDirectoryNotFoundException(error) {
-  if (error is! DirectoryException) return false;
+  if (error is! FileSystemException) return false;
 
   // See dartbug.com/12461 and tests/standalone/io/directory_error_test.dart.
   var notFoundCode = Platform.operatingSystem == "windows" ? 3 : 2;