Issue 5395 - Make sure element hiding emulation doesn't degrade website performance too much

test/browser/elemHideEmulation.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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 243 matching lines @@
 {
   let toHide = createElementWithStyle("{}");
   applyElemHideEmulation(
     [":-abp-properties(background-color: rgb(0, 0, 0))"]
   ).then(() =>
   {
     expectVisible(test, toHide);
     insertStyleRule("#" + toHide.id + " {background-color: #000}");
     return new Promise((resolve, reject) =>
     {
+      // Re-evaluation will only happen after a few seconds
+      expectVisible(test, toHide);
       window.setTimeout(() =>
       {
         expectHidden(test, toHide);
         resolve();
-      }, 0);
+      }, 4000);
     });
   }).catch(unexpectedError.bind(test)).then(() => test.done());
 };
 
 exports.testPseudoClassHasSelector = function(test)
 {
   let toHide = createElementWithStyle("{}");
   applyElemHideEmulation(
     ["div:-abp-has(div)"]
   ).then(() =>
@@ skipping 118 matching lines @@
   let parent = createElementWithStyle("{}");
   let child = createElementWithStyle("{background-color: #000}", parent);
   applyElemHideEmulation(
     ["div:-abp-has(:-abp-properties(background-color: rgb(0, 0, 0)))"]
   ).then(() =>
   {
     expectVisible(test, child);
     expectHidden(test, parent);
   }).catch(unexpectedError.bind(test)).then(() => test.done());
 };