Modify type on _onBatch to reflect call argument types

pkgs/watcher/CHANGELOG.md

diff --git a/pkgs/watcher/CHANGELOG.md b/pkgs/watcher/CHANGELOG.md
index f07ceaf..89da684 100644
--- a/pkgs/watcher/CHANGELOG.md
+++ b/pkgs/watcher/CHANGELOG.md
@@ -1,3 +1,8 @@
+# 0.9.7+5
+
+* Change the type on a local function (_onBatch) to reflect the fact that its
+  caller does not statically guarantee its contract.
+
 # 0.9.7+4
 
 * Declare support for `async` 2.0.0.

pkgs/watcher/lib/src/directory_watcher/linux.dart

diff --git a/pkgs/watcher/lib/src/directory_watcher/linux.dart b/pkgs/watcher/lib/src/directory_watcher/linux.dart
index df1365c..c291aad 100644
--- a/pkgs/watcher/lib/src/directory_watcher/linux.dart
+++ b/pkgs/watcher/lib/src/directory_watcher/linux.dart
@@ -127,7 +127,8 @@
   }
 
   /// The callback that's run when a batch of changes comes in.
-  void _onBatch(List<FileSystemEvent> batch) {
+  void _onBatch(Object data) {
+    var batch = data as List<FileSystemEvent>;
     var files = new Set<String>();
     var dirs = new Set<String>();
     var changed = new Set<String>();

pkgs/watcher/pubspec.yaml

diff --git a/pkgs/watcher/pubspec.yaml b/pkgs/watcher/pubspec.yaml
index 15c51c6..41fbd8b 100644
--- a/pkgs/watcher/pubspec.yaml
+++ b/pkgs/watcher/pubspec.yaml
@@ -1,5 +1,5 @@
 name: watcher
-version: 0.9.7+4
+version: 0.9.7+5
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/dart-lang/watcher
 description: >