Move 'use strict' to file level

Change-Id: I1f0dae4aa168e77c112bcd3688c98b84e4ce5f36
diff --git a/dev/js/src/plugin/service.js b/dev/js/src/plugin/service.js
index 3a39c4d..a76b2e4 100644
--- a/dev/js/src/plugin/service.js
+++ b/dev/js/src/plugin/service.js
@@ -1,5 +1,6 @@
+"use strict";
+
 define(function () {
-  "use strict";
 
   // Limit the supported sandbox permissions, especially
   // to disallow 'same-origin'.