Add Coveralls badge to README.md (#4700)
diff --git a/README.md b/README.md
index b8ba39c..300007d 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,7 @@
=======
[](https://travis-ci.org/flutter/flutter)
+[](https://coveralls.io/github/flutter/flutter?branch=master)
[](http://issuestats.com/github/flutter/flutter)
[](http://issuestats.com/github/flutter/flutter)