Merge pull request #970 from dart-lang/srawlins-patch-1

Remove unused dart:async imports.
diff --git a/pubspec.yaml b/pubspec.yaml
index 5221cc3..776e52a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: dart_style
 # Note: See tool/grind.dart for how to bump the version.
-version: 1.3.9
+version: 1.3.10-dev
 description: >-
   Opinionated, automatic Dart source code formatter.
   Provides an API and a CLI tool.