Issue 5864 - Remove previous style sheet before adding one

lib/cssInjection.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 25 matching lines @@
     code: styleSheet,
     cssOrigin: "user",
     frameId,
     matchAboutBlank: true,
     runAt: "document_start"
   });
 }
 
 function removeStyleSheet(tabId, frameId, styleSheet)
 {
-  chrome.tabs.removeCSS(tabId, {
+  browser.tabs.removeCSS(tabId, {
     code: styleSheet,
     cssOrigin: "user",
     frameId,
     matchAboutBlank: true
   });
 }
 
-function replaceStyleSheet(tabId, frameId, oldStyleSheet, newStyleSheet)
-{
-  // Add the new style sheet first to avoid previously hidden elements from
-  // reappearing momentarily.
-  if (newStyleSheet)
-    addStyleSheet(tabId, frameId, newStyleSheet);
-
-  // Sometimes the old and new style sheets can be exactly the same. In such a
-  // case, do not remove the "old" style sheet, because it is in fact the new
-  // style sheet now.
-  if (oldStyleSheet && oldStyleSheet != newStyleSheet)
-    removeStyleSheet(tabId, frameId, oldStyleSheet);
-}
-
-function updateFrameStyles(pageId, frameId, selectors, groupName)
+function updateFrameStyles(tabId, frameId, selectors, groupName)
 {
   let styleSheet = null;
   if (selectors.length > 0)
     styleSheet = selectors.join(", ") + "{display: none !important;}";
 
-  let frame = ext.getFrame(pageId, frameId);
+  let frame = ext.getFrame(tabId, frameId);
   if (!frame.injectedStyleSheets)
     frame.injectedStyleSheets = new Map();
 
   let oldStyleSheet = frame.injectedStyleSheets.get(groupName);
 
-  // Ideally we would compare the old and new style sheets and skip this call
+  // Ideally we would compare the old and new style sheets and skip this code
   // if they're the same, but the old style sheet can be a leftover from a
   // previous instance of the frame. We must add the new style sheet
   // regardless.
-  replaceStyleSheet(pageId, frameId, oldStyleSheet, styleSheet);
+
+  // Add the new style sheet first to keep previously hidden elements from
+  // reappearing momentarily.
+  if (styleSheet)
+    addStyleSheet(tabId, frameId, styleSheet);
+
+  // Sometimes the old and new style sheets can be exactly the same. In such a
+  // case, do not remove the "old" style sheet, because it is in fact the new
+  // style sheet now.
+  if (oldStyleSheet && oldStyleSheet != styleSheet)
+    removeStyleSheet(tabId, frameId, oldStyleSheet);
+
   frame.injectedStyleSheets.set(groupName, styleSheet);
 }
 
 port.on("elemhide.getSelectors", (message, sender) =>
 {
   let selectors = [];
   let emulatedPatterns = [];
   let trace = devtools && devtools.hasPanel(sender.page);
   let inline = !userStyleSheetsSupported;
 
@@ skipping 22 matching lines @@
     response.selectors = selectors;
 
   return response;
 });
 
 port.on("elemhide.injectSelectors", (message, sender) =>
 {
   updateFrameStyles(sender.page.id, sender.frame.id, message.selectors,
                     message.groupName);
 });