wrap autofill content script in function

src/autofillContent.js

@@ -1,4 +1,5 @@
-/*
+!(function() {
+    /*
     1Password Extension
 
     Lovingly handcrafted by Dave Teare, Michael Fey, Rad Azzouz, and Roustem Karimov.
@@ -87,3 +88,4 @@ chrome.runtime.onMessage.addListener(function (msg, sender, sendResponse) {
             return true;
         }
     });
+})();