Issue 6504 - Remove useInlineStyles for now

lib/content/elemHideEmulation.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 586 matching lines @@
 {
   return patterns.some(pattern => pattern.dependsOnCharacterData);
 }
 
 function ElemHideEmulation(addSelectorsFunc, hideElemsFunc)
 {
   this.document = document;
   this.addSelectorsFunc = addSelectorsFunc;
   this.hideElemsFunc = hideElemsFunc;
   this.observer = new MutationObserver(this.observe.bind(this));
-
-  // This flag is supposed to indicate whether we should prefer setting the
-  // style attribute of the element over using CSS selectors. It is set by the
-  // web extension if the tabs.removeCSS API is available (Firefox 53+). But
-  // because of issues with performance (see #6504), we are ignoring the value
-  // of this flag for now; we always set the style attribute.
-  // https://issues.adblockplus.org/ticket/6504#comment:9
-  this.useInlineStyles = true;

[hub, 2018/08/10 19:43:16]

so if we don't use it, and since the code below gets removed, then why doesn't
this property get removed?

[Manish Jethani, 2018/08/14 16:50:16]

I left it there with a comment sorta hoping that someday we might get around to
using it. We could just as well remove it entirely.

What do you think?

[hub, 2018/08/14 17:24:41]

Since you remove the code below, I believe it is pointless to leave this here.

[Manish Jethani, 2018/08/14 17:46:22]

Sounds OK to me.

Done.

 }
 
 ElemHideEmulation.prototype = {
   isSameOrigin(stylesheet)
   {
     try
     {
       return new URL(stylesheet.href).origin == this.document.location.origin;
     }
     catch (e)
@@ skipping 98 matching lines @@
 
     // If neither any style sheets nor any DOM mutations have been specified,
     // do full processing.
     if (!stylesheets && !mutations)
       stylesheets = this.document.styleSheets;
 
     // If there are any DOM mutations and any of the patterns depends on both
     // style sheets and the DOM (e.g. -abp-has(-abp-properties)), find all the
     // rules in every style sheet in the document, because we need to run
     // querySelectorAll afterwards. On the other hand, if we only have patterns
-    // that depend on either styles or DOM both not both
-    // (e.g. -abp-properties or -abp-contains), we can skip this part.
+    // that depend on either styles or DOM both not both (e.g. -abp-contains),
+    // we can skip this part.
     if (mutations && patterns.some(pattern => pattern.dependsOnStylesAndDOM))
       stylesheets = this.document.styleSheets;
 
     for (let stylesheet of stylesheets || [])
     {
       // Explicitly ignore third-party stylesheets to ensure consistent behavior
       // between Firefox and Chrome.
       if (!this.isSameOrigin(stylesheet))
         continue;
 
@@ skipping 47 matching lines @@
 
         pattern = patterns.shift();
 
         let evaluationTargets = targets;
 
         // If the pattern appears to contain any sibling combinators, we can't
         // easily optimize based on the mutation targets. Since this is a
         // special case, skip the optimization. By setting it to null here we
         // make sure we process the entire DOM.
         if (pattern.maybeContainsSiblingCombinators)
-          evaluationTargets = null;
-
-        // Ignore mutation targets when using style sheets, because we may have
-        // to update all the CSS selectors.
-        if (!this.useInlineStyles)
           evaluationTargets = null;
 
         generator = evaluate(pattern.selectors, 0, "",
                              this.document, cssStyles, evaluationTargets);
       }
       for (let selector of generator)
       {
         if (selector != null)
         {
           for (let element of this.document.querySelectorAll(selector))
@@ skipping 161 matching lines @@
           characterData: shouldObserveCharacterData(this.patterns),
           subtree: true
         }
       );
       this.document.addEventListener("load", this.onLoad.bind(this), true);
     }
   }
 };
 
 exports.ElemHideEmulation = ElemHideEmulation;