Issue 6997 - Use createStyleSheet implementation from core

lib/contentFiltering.js

Index: lib/contentFiltering.js
===================================================================
--- a/lib/contentFiltering.js
+++ b/lib/contentFiltering.js
@@ -15,17 +15,17 @@
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 /** @module contentFiltering */
 
 "use strict";
 
 const {RegExpFilter} = require("../adblockpluscore/lib/filterClasses");
-const {ElemHide} = require("../adblockpluscore/lib/elemHide");
+const {ElemHide, createStyleSheet} = require("../adblockpluscore/lib/elemHide");
 const {ElemHideEmulation} = require("../adblockpluscore/lib/elemHideEmulation");
 const {filterNotifier} = require("../adblockpluscore/lib/filterNotifier");
 const {Snippets, compileScript} = require("../adblockpluscore/lib/snippets");
 const {checkWhitelisted} = require("./whitelisting");
 const {extractHostFromFrame} = require("./url");
 const {port} = require("./messaging");
 const {HitLogger, logRequest} = require("./hitLogger");
 const info = require("info");
@@ -38,44 +38,16 @@
 
 const selectorGroupSize = 1024;
 
 let userStyleSheetsSupported = true;
 
 let snippetsLibrarySource = "";
 let executableCode = new Map();
 
-function* splitSelectors(selectors)
-{
-  // Chromium's Blink engine supports only up to 8,192 simple selectors, and
-  // even fewer compound selectors, in a rule. The exact number of selectors
-  // that would work depends on their sizes (e.g. "#foo .bar" has a size of 2).
-  // Since we don't know the sizes of the selectors here, we simply split them
-  // into groups of 1,024, based on the reasonable assumption that the average
-  // selector won't have a size greater than 8. The alternative would be to
-  // calculate the sizes of the selectors and divide them up accordingly, but
-  // this approach is more efficient and has worked well in practice. In theory
-  // this could still lead to some selectors not working on Chromium, but it is
-  // highly unlikely.
-  // See issue #6298 and https://crbug.com/804179
-  for (let i = 0; i < selectors.length; i += selectorGroupSize)
-    yield selectors.slice(i, i + selectorGroupSize);
-}
-
-function* createRules(selectors)
-{
-  for (let selectorGroup of splitSelectors(selectors))
-    yield selectorGroup.join(", ") + " {display: none !important;}";
-}
-
-function createStyleSheet(selectors)
-{
-  return Array.from(createRules(selectors)).join("\n");
-}
-
 function addStyleSheet(tabId, frameId, styleSheet)
 {
   try
   {
     let promise = browser.tabs.insertCSS(tabId, {
       code: styleSheet,
       cssOrigin: "user",
       frameId,