Noissue - Delete properties instead of setting to null

lib/filterClasses.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 443 matching lines @@
           }
 
           if (!domains)
             domains = new Map();
 
           domains.set(domain, include);
         }
         if (domains)
           domains.set("", !hasIncludes);
       }
-
-      this.domainSource = null;
     }
 
     Object.defineProperty(this, "domains", {value: domains, enumerable: true});
+    delete this.domainSource;
     return this.domains;
   },
 
   /**
    * Array containing public keys of websites that this filter should apply to
    * @type {?string[]}
    */
   sitekeys: null,
 
   /**
@@ skipping 225 matching lines @@
   {
     // Despite this property being cached, the getter is called
     // several times on Safari, due to WebKit bug 132872
     let prop = Object.getOwnPropertyDescriptor(this, "sitekeys");
     if (prop)
       return prop.value;
 
     let sitekeys = null;
 
     if (this.sitekeySource)
-    {
       sitekeys = this.sitekeySource.split("|");
-      this.sitekeySource = null;
-    }
 
     Object.defineProperty(
       this, "sitekeys", {value: sitekeys, enumerable: true}
     );
+    delete this.sitekeySource;
     return this.sitekeys;
   },
 
   /**
    * Tests whether the URL matches this filter
    * @param {string} location URL to be tested
    * @param {number} typeMask bitmask of content / request types to match
    * @param {string} [docDomain] domain name of the document that loads the URL
    * @param {boolean} [thirdParty] should be true if the URL is a third-party
    *                               request
@@ skipping 382 matching lines @@
  */
 function ElemHideEmulationFilter(text, domains, selector)
 {
   ElemHideBase.call(this, text, domains, selector);
 }
 exports.ElemHideEmulationFilter = ElemHideEmulationFilter;
 
 ElemHideEmulationFilter.prototype = extend(ElemHideBase, {
   type: "elemhideemulation"
 });