Issue 5464 - Ignore and whitelist WebRTC if not supported

lib/abp2blocklist.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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 1296 matching lines @@
     convertFilterAddRules(blockingRules, filter, "block", true,
                           requestFilterExceptionDomains);
   }
 
   for (let filter of this.requestExceptions)
   {
     convertFilterAddRules(blockingExceptionRules, filter,
                           "ignore-previous-rules", true);
   }
 
+  // If WebRTC is not supported, we still end up generating a lot of rules with
+  // a generic URL scheme pattern that covers WebRTC anyway. In order to avoid
+  // inadvertently blocking any WebRTC requests, we must add exceptions here
+  // for WebRTC URLs. This is not required when WebRTC is supported, because in
+  // that case we explicitly check if the filter covers WebRTC.
   if (!typeMap.WEBRTC)
   {
-    urlSchemeExceptionRules.push([
+    urlSchemeExceptionRules.push(
       {
         trigger: {"url-filter": "^stuns?:"},
         action: {type: "ignore-previous-rules"}
       },
       {
         trigger: {"url-filter": "^turns?:"},
         action: {type: "ignore-previous-rules"}
       }
-    ]);
+    );
   }
 
   return async(ruleGroups, (group, index) => () =>
   {
     let next = () =>
     {
       if (index == ruleGroups.length - 1)
         return ruleGroups.reduce((all, rules) => all.concat(rules), []);
     };
 
     if (this.options.merge == "all" ||
         (this.options.merge == "auto" &&
          ruleGroups.reduce((n, group) => n + group.length, 0) > 50000))
     {
       return mergeRules(ruleGroups[index], this.options.merge == "all")
       .then(rules =>
       {
         ruleGroups[index] = rules;
         return next();
       });
     }
 
     return next();
   });
 };