Issue 4795 - Use modern JavaScript syntax

ext/background.js

Index: ext/background.js
diff --git a/ext/background.js b/ext/background.js
index f6ce8ce075bae22f0569a1cdd741ee29646ba580..cfe28fe50f8c78cebfa0f450453c58e467380461 100644
--- a/ext/background.js
+++ b/ext/background.js
@@ -15,12 +15,13 @@
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-(function()
+"use strict";
+
 {
-  var nonEmptyPageMaps = Object.create(null);
-  var pageMapCounter = 0;
+  let nonEmptyPageMaps = Object.create(null);
+  let pageMapCounter = 0;
 
-  var PageMap = ext.PageMap = function()
+  let PageMap = ext.PageMap = function()
   {
     this._map = Object.create(null);
     this._id = ++pageMapCounter;
@@ -52,7 +53,7 @@
     },
     clear: function()
     {
-      for (var id in this._map)
+      for (let id in this._map)
         this._delete(id);
     },
     delete: function(page)
@@ -61,9 +62,9 @@
     }
   };
 
-  ext._removeFromAllPageMaps = function(pageId)
+  ext._removeFromAllPageMaps = pageId =>
   {
-    for (var pageMapId in nonEmptyPageMaps)
+    for (let pageMapId in nonEmptyPageMaps)
       nonEmptyPageMaps[pageMapId]._delete(pageId);
   };
-})();
+}