Fix travis (dart-lang/clock#7)

diff --git a/pkgs/clock/.travis.yml b/pkgs/clock/.travis.yml
index 70fa656..a9f76c7 100644
--- a/pkgs/clock/.travis.yml
+++ b/pkgs/clock/.travis.yml
@@ -20,6 +20,7 @@
   include:
   - dart: dev
     dart_task: dartanalyzer
+  - dart: dev
     dart_task: dartfmt
 
 # Only building master means that we don't run two builds for each pull request.