Ensure procedural filters are applied at least once

Related feedback:
- https://github.com/uBlockOrigin/uBlock-issues/discussions/2261#discussioncomment-4123057

Cosmetic filters will be applied unconditionally at least
once at DOMContentLoaded time.

src/js/contentscript-extra.js

@@ -441,8 +441,6 @@ PSelectorRoot.prototype.hit = false;
 class ProceduralFilterer {
     constructor(domFilterer) {
         this.domFilterer = domFilterer;
-        this.domIsReady = false;
-        this.domIsWatched = false;
         this.mustApplySelectors = false;
         this.selectors = new Map();
         this.masterToken = vAPI.randomToken();
@@ -455,7 +453,7 @@ class ProceduralFilterer {
 
     addProceduralSelectors(selectors) {
         const addedSelectors = [];
-        let mustCommit = this.domIsWatched;
+        let mustCommit = false;
         for ( const selector of selectors ) {
             if ( this.selectors.has(selector.raw) ) { continue; }
             let style, styleToken;
@@ -483,9 +481,7 @@ class ProceduralFilterer {
     }
 
     commitNow() {
-        if ( this.selectors.size === 0 || this.domIsReady === false ) {
-            return;
-        }
+        if ( this.selectors.size === 0 ) { return; }
 
         this.mustApplySelectors = false;
 
@@ -567,8 +563,6 @@ class ProceduralFilterer {
     }
 
     onDOMCreated() {
-        this.domIsReady = true;
-        this.domFilterer.commit();
     }
 
     onDOMChanged(addedNodes, removedNodes) {

src/js/contentscript.js

@@ -495,7 +495,6 @@ vAPI.DOMFilterer = class {
         this.commitTimer = new vAPI.SafeAnimationFrame(
             ( ) => { this.commitNow(); }
         );
-        this.domIsReady = document.readyState !== 'loading';
         this.disabled = false;
         this.listeners = [];
         this.stylesheets = [];
@@ -503,18 +502,6 @@ vAPI.DOMFilterer = class {
         this.exceptions = [];
         this.convertedProceduralFilters = [];
         this.proceduralFilterer = null;
-        // https://github.com/uBlockOrigin/uBlock-issues/issues/167
-        //   By the time the DOMContentLoaded is fired, the content script might
-        //   have been disconnected from the background page. Unclear why this
-        //   would happen, so far seems to be a Chromium-specific behavior at
-        //   launch time.
-        if ( this.domIsReady !== true ) {
-            document.addEventListener('DOMContentLoaded', ( ) => {
-                if ( vAPI instanceof Object === false ) { return; }
-                this.domIsReady = true;
-                this.commit();
-            });
-        }
     }
 
     explodeCSS(css) {
@@ -1241,6 +1228,10 @@ vAPI.DOMFilterer = class {
             what: 'shouldRenderNoscriptTags',
         });
 
+        if ( vAPI.domFilterer instanceof Object ) {
+            vAPI.domFilterer.commitNow();
+        }
+
         if ( vAPI.domWatcher instanceof Object ) {
             vAPI.domWatcher.start();
         }