Issue 5175 - Reject element hiding filter with empty domain names

compiled/filter/ActiveFilter.cpp

 /*
  * 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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <cstdio>
 
 #include "ActiveFilter.h"
 #include "../StringScanner.h"
 
-namespace
-{
-  const DependentString DEFAULT_DOMAIN(u""_str);
-}
+ABP_NS_USING
+
+const DependentString ActiveFilter::DEFAULT_DOMAIN(u""_str);
 
 ActiveFilter::ActiveFilter(Type type, const String& text, bool ignoreTrailingDot)
     : Filter(type, text), mIgnoreTrailingDot(ignoreTrailingDot),
       mDisabled(false), mHitCount(0), mLastHit(0)
 {
 }
 
 ActiveFilter::DomainMap* ActiveFilter::GetDomains() const
 {
   return mDomains.get();
@@ skipping 174 matching lines @@
     result.append(u'\n');
   }
   if (mLastHit)
   {
     result.append(u"lastHit="_str);
     result.append(mLastHit);
     result.append(u'\n');
   }
   return result;
 }