Use firefox < 53 in travis

fredj · fredj · commit 4a6f427df71f · 2017-04-20T10:58:12.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -6,7 +6,7 @@ node_js:
   - "6.1"
 
 addons:
-  firefox: "latest"
+  firefox: "52.0"
 
 cache:
   directories:
