Issue 4795 - Use modern JavaScript syntax

chrome/ext/popup.js

-(function()
 {
-  var backgroundPage = chrome.extension.getBackgroundPage();
+  let backgroundPage = chrome.extension.getBackgroundPage();
   window.ext = Object.create(backgroundPage.ext);
 
-  ext.closePopup = function()
+  ext.closePopup = () =>
   {
     window.close();
   };
 
   // We have to override ext.backgroundPage, because in order
   // to send messages the local "chrome" namespace must be used.
   ext.backgroundPage = {
     sendMessage: chrome.runtime.sendMessage,
 
-    getWindow: function()
-    {
-      return backgroundPage;
-    }
+    getWindow: () => backgroundPage
   };
-})();
+}