Attempt to fix Hint compatibility problem (WIP)

Change-Id: I3016afc2f74b90c223dd4f8f2386b71aab1eedcd
diff --git a/dev/js/src/hint/lengthField.js b/dev/js/src/hint/lengthField.js
index 541b917..79c7b7d 100644
--- a/dev/js/src/hint/lengthField.js
+++ b/dev/js/src/hint/lengthField.js
@@ -1,3 +1,5 @@
+"use strict";
+
 define(['menu/lengthField', 'util'], function (lengthFieldClass) {
   return {