Use node 9 for tests

kern · kern · commit fa2aa646b0f1 · 2018-06-08T13:38:54.000-07:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,6 +1,6 @@
 language: node_js
 node_js:
-  - node
+  - "9"
 script:
   - yarn run check
   - yarn run lint
