Noissue - Avoid delete operator on RegExpFilter.regexpSource

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 651 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, "regexp");
     if (prop)
       return prop.value;
 
     let source = Filter.toRegExp(this.regexpSource);
     let regexp = new RegExp(source, this.matchCase ? "" : "i");
     Object.defineProperty(this, "regexp", {value: regexp});
-    delete this.regexpSource;
+    this.regexpSource = null;
     return regexp;
   },
   /**
    * Content types the filter applies to, combination of values from
    * RegExpFilter.typeMap
    * @type {number}
    */
   contentType: 0x7FFFFFFF,
   /**
    * Defines whether the filter should distinguish between lower and
@@ skipping 431 matching lines @@
  */
 function ElemHideEmulationFilter(text, domains, selector)
 {
   ElemHideBase.call(this, text, domains, selector);
 }
 exports.ElemHideEmulationFilter = ElemHideEmulationFilter;
 
 ElemHideEmulationFilter.prototype = extend(ElemHideBase, {
   type: "elemhideemulation"
 });