Issue 4795 - Use modern JavaScript syntax

chrome/ext/content.js

-chrome.runtime.onMessage.addListener(function(message, sender, sendResponse)
+"use strict";
+
+chrome.runtime.onMessage.addListener((message, sender, sendResponse) =>
 {
   return ext.onMessage._dispatch(message, {}, sendResponse).indexOf(true) != -1;
 });
 
-ext.onExtensionUnloaded = (function()
+ext.onExtensionUnloaded = (() =>
 {
-  var port = null;
+  let port = null;
 
   return {
-    addListener: function(listener)
+    addListener(listener)
     {
       if (!port)
         port = chrome.runtime.connect();
 
       // When the extension is reloaded, disabled or uninstalled the
       // background page dies and automatically disconnects all ports
       port.onDisconnect.addListener(listener);
     },
-    removeListener: function(listener)
+    removeListener(listener)
     {
       if (port)
       {
         port.onDisconnect.removeListener(listener);
 
         if (!port.onDisconnect.hasListeners())
         {
           port.disconnect();
           port = null;
         }
       }
     }
   };
 })();