Noissue - Ensure ElemHideBase::GetSelector() doesn't misuse a read only string

compiled/filter/ElemHideBase.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
@@ skipping 141 matching lines @@
         break;
       }
     }
 
     return result;
   }
 }
 
 OwnedString ElemHideBase::GetSelector() const
 {
-  DependentString selector = mData.GetSelector(mText);
+  const DependentString selector = mData.GetSelector(mText);
   String::size_type replacementCount = 0;
   for (String::size_type i = 0; i < selector.length(); i++)
     if (selector[i] == '}' || selector[i] == '{')
       replacementCount++;
   if (replacementCount)
     return EscapeCurlies(replacementCount, selector);
 
   return OwnedString(selector);
 }
 
 OwnedString ElemHideBase::GetSelectorDomain() const
 {
   /* TODO this is inefficient */
   OwnedString result;
   if (mDomains)
   {
     for (const auto& item : *mDomains)
     {
       if (item.second && !item.first.empty())
       {
         if (!result.empty())
           result.append(u',');
         result.append(item.first);
       }
     }
   }
   return result;
 }