Issue 3761 - Don't clear user input when filter validation failed

messageResponder.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 166 matching lines @@
           listenerFilters.app = message.filter;
         else
           delete listenerFilters.app;
         break;
       case "app.open":
         if (message.what == "options")
           ext.showOptions();
         break;
       case "filters.add":
         var result = require("filterValidation").parseFilter(message.text);
+        var errors = [];
         if (result.error)
-          sendMessage("app", "error", [result.error.toString()], sender.page);
+          errors.push(result.error.toString());
         else if (result.filter)
           FilterStorage.addFilter(result.filter);
+        callback(errors);
         break;
       case "filters.blocked":
         var filter = defaultMatcher.matchesAny(message.url, message.requestType,
           message.docDomain, message.thirdParty);
         callback(filter instanceof BlockingFilter);
         break;
       case "filters.get":
         if (message.what == "cssproperties")
         {
           var filters = [];
@@ skipping 29 matching lines @@
       case "filters.importRaw":
         var result = require("filterValidation").parseFilters(message.text);
         var errors = [];
         for (var i = 0; i < result.errors.length; i++)
         {
           var error = result.errors[i];
           if (error.type != "unexpected-filter-list-header")
             errors.push(error.toString());
         }
 
+        callback(errors);
         if (errors.length > 0)
-        {
-          sendMessage("app", "error", errors, sender.page);
           return;
-        }
 
         var seenFilter = Object.create(null);
         for (var i = 0; i < result.filters.length; i++)
         {
           var filter = result.filters[i];
           FilterStorage.addFilter(filter);
           seenFilter[filter.text] = null;
         }
 
         for (var i = 0; i < FilterStorage.subscriptions.length; i++)
@@ skipping 107 matching lines @@
           if (subscription instanceof DownloadableSubscription)
             Synchronizer.execute(subscription, true);
         }
         break;
       case "subscriptions.isDownloading":
         callback(Synchronizer.isExecuting(message.url));
         break;
     }
   });
 })(this);