Issue 6619 - Qualify CSS selectors in document style sheet correctly

lib/content/elemHideEmulation.js

Index: lib/content/elemHideEmulation.js
===================================================================
--- a/lib/content/elemHideEmulation.js
+++ b/lib/content/elemHideEmulation.js
@@ -12,17 +12,18 @@
  * 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/>.
  */
 
 "use strict";
 
-const {textToRegExp, filterToRegExp, splitSelector} = require("../common");
+const {textToRegExp, filterToRegExp, splitSelector,
+       qualifySelector} = require("../common");
 const {indexOf} = require("../coreUtils");
 
 let MIN_INVOCATION_INTERVAL = 3000;
 const MAX_SYNCHRONOUS_PROCESSING_TIME = 50;
 const abpSelectorRegexp = /:-abp-([\w-]+)\(/i;
 
 function getCachedPropertyValue(object, name, defaultValueFunc = () => {})
 {
@@ -381,17 +382,17 @@
           if (subSelector.startsWith("*") &&
               !incompletePrefixRegexp.test(prefix))
           {
             subSelector = subSelector.substr(1);
           }
           let idx = subSelector.lastIndexOf("::");
           if (idx != -1)
             subSelector = subSelector.substr(0, idx);
-          yield prefix + subSelector;
+          yield qualifySelector(subSelector, prefix);
         }
   },
 
   *getSelectors(prefix, subtree, styles)
   {
     for (let selector of this.findPropsSelectors(styles, prefix, this._regexp))
       yield [selector, subtree];
   }