Issue 6437 - Apply :-abp-contains() to matching roots only

lib/content/elemHideEmulation.js

 /*
  * 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 312 matching lines @@
     for (let element of this.getElements(prefix, subtree, styles))
       yield [makeSelector(element, ""), subtree];
   },
 
   *getElements(prefix, subtree, styles)
   {
     let actualPrefix = (!prefix || incompletePrefixRegexp.test(prefix)) ?
         prefix + "*" : prefix;
 
     let elements = scopedQuerySelectorAll(subtree, actualPrefix);
+
     if (elements)
     {
+      let lastRoot = null;
       for (let element of elements)
       {
+        // For a filter like div:-abp-contains(Hello) and a subtree like
+        // <div id="a"><div id="b"><div id="c">Hello</div></div></div>
+        // we're only interested in div#a
+        if (lastRoot && lastRoot.contains(element))
+        {
+          yield null;
+          continue;
+        }
+
+        lastRoot = element;
+
         if (this._regexp && this._regexp.test(element.textContent))
           yield element;
         else
           yield null;
       }
     }
   }
 };
 
 function PropsSelector(propertyExpression)
@@ skipping 462 matching lines @@
           characterData: shouldObserveCharacterData(this.patterns),
           subtree: true
         }
       );
       this.document.addEventListener("load", this.onLoad.bind(this), true);
     }
   }
 };
 
 exports.ElemHideEmulation = ElemHideEmulation;