Issue 4795 - Use modern JavaScript syntax

lib/utils.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 29 matching lines @@
     {
       setTimeout(callback, 0);
     }
   },
   get appLocale()
   {
     let locale = ext.i18n.getMessage("@@ui_locale").replace(/_/g, "-");
     Object.defineProperty(this, "appLocale", {value: locale, enumerable: true});
     return this.appLocale;
   },
-  // We cannot calculate MD5 checksums yet :-(
   generateChecksum(lines)
   {
+    // We cannot calculate MD5 checksums yet :-(
     return null;
   },
   checkLocalePrefixMatch(prefixes)
   {
     if (!prefixes)
       return null;
 
     for (let prefix of prefixes.split(","))
       if (new RegExp("^" + prefix + "\\b").test(this.appLocale))
         return prefix;
 
     return null;
   },
 
   chooseFilterSubscription(subscriptions)
   {
     let selectedItem = null;
     let selectedPrefix = null;
     let matchCount = 0;
     for (let subscription of subscriptions)
     {
       if (!selectedItem)
         selectedItem = subscription;
 
-      let prefix = require("utils").Utils.checkLocalePrefixMatch(subscription.getAttribute("prefixes"));
+      let prefix = Utils.checkLocalePrefixMatch(subscription.getAttribute("prefixes"));
       if (prefix)
       {
         if (!selectedPrefix || selectedPrefix.length < prefix.length)
         {
           selectedItem = subscription;
           selectedPrefix = prefix;
           matchCount = 1;
         }
         else if (selectedPrefix && selectedPrefix.length == prefix.length)
         {
           matchCount++;
 
           // If multiple items have a matching prefix of the same length:
           // Select one of the items randomly, probability should be the same
           // for all items. So we replace the previous match here with
           // probability 1/N (N being the number of matches).
           if (Math.random() * matchCount < 1)
           {
             selectedItem = subscription;
             selectedPrefix = prefix;
           }
         }
       }
     }
     return selectedItem;
   },
 
   getDocLink(linkID)
   {
-    const {Prefs} = require("prefs");
-    let docLink = Prefs.documentation_link;
+    let docLink = require("prefs").Prefs.documentation_link;
     return docLink.replace(/%LINK%/g, linkID).replace(/%LANG%/g, Utils.appLocale);
   },
 
   yield()
   {
   }
 };