Fix --watch option with node on Mac OS (#402)

Closes #399

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 * Don't emit ANSI codes to Windows terminals that don't support them.
 
+* Fix a bug where `--watch` crashed on Mac OS.
+
 ## 1.9.0
 
 ### Node API

lib/src/io/node.dart

@@ -252,11 +252,11 @@ Future<Stream<WatchEvent>> watchDir(String path, {bool poll: false}) {
   watcher
     ..on(
         'add',
-        allowInterop((String path, _) =>
+        allowInterop((String path, [_]) =>
             controller?.add(new WatchEvent(ChangeType.ADD, path))))
     ..on(
         'change',
-        allowInterop((String path, _) =>
+        allowInterop((String path, [_]) =>
             controller?.add(new WatchEvent(ChangeType.MODIFY, path))))
     ..on(
         'unlink',

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.9.1-dev
+version: 1.9.1
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass