Issue 6538, 6781 - Allow snippets only from circumvention lists

lib/filterListener.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 124 matching lines @@
  * if necessary.
  * @param {Filter} filter filter that has been added
  */
 function addFilter(filter)
 {
   if (!(filter instanceof ActiveFilter) || filter.disabled)
     return;
 
   let hasEnabled = false;
   let allowSnippets = false;
   for (let i = 0; i < filter.subscriptions.length; i++)

[kzar, 2018/07/10 14:38:35]

Nit: `for (let subscription of filter.subscriptions)`

[Manish Jethani, 2018/07/10 18:33:22]

I did this initially and then reverted it. There's a similar loop in the
removeFilter function. The way I see it, this would be an unrelated change. I
think it should be done separately as a "no issue", also in the removeFilter
function.

[kzar, 2018/07/10 18:56:00]

Sure it's an unrelated change, but you're changing the entire loop anyway, it
seems crazy not to fix this at the same time IMO.

[Manish Jethani, 2018/07/11 15:07:03]

There are some performance implications of for..of [1] which really matters on
mobile. I would like to properly test/benchmark it and make the change in both
places.

[1]:
https://www.incredible-web.com/blog/performance-of-for-loops-with-javascript/

[kzar, 2018/07/11 17:22:07]

Fine.

   {
     let subscription = filter.subscriptions[i];
 
     if (!subscription.disabled)
     {
       hasEnabled = true;
 
       // Allow snippets to be executed only by the circumvention lists or the
       // user's own filters.
-      if (!allowSnippets &&
-          (subscription.type == "circumvention" ||
-           subscription instanceof SpecialSubscription))
+      if (subscription.type == "circumvention" ||
+          subscription instanceof SpecialSubscription)
       {
         allowSnippets = true;
         break;
       }
     }
   }
   if (!hasEnabled)
     return;
 
   if (filter instanceof RegExpFilter)
@@ skipping 169 matching lines @@
   {
     if (!subscription.disabled)
       addFilters(subscription.filters);
   }
 }
 
 function onSave()
 {
   isDirty = 0;
 }