Add ability to linger for remove-class scriptlet

Similar to related change for the `remove-attr` scriptlet:
- 0f330c7

Related feedback:
- https://www.reddit.com/r/uBlockOrigin/comments/nsroaw/some_elements_isare_not_removed_after_the_cookie/

assets/resources/scriptlets.js

@@ -764,7 +764,10 @@
  if ( selector === '' || selector === '{{2}}' ) {
  selector = '.' + tokens.map(a => CSS.escape(a)).join(',.');
  }
+ let behavior = '{{3}}';
+ let timer;
  const rmclass = function() {
+ timer = undefined;
  try {
  const nodes = document.querySelectorAll(selector);
  for ( const node of nodes ) {
@@ -773,14 +776,39 @@
  } catch(ex) {
  }
  };
- if ( document.readyState === 'loading' ) {
- window.addEventListener(
- 'DOMContentLoaded',
- rmclass,
- { capture: true, once: true }
- );
- } else {
+ const mutationHandler = mutations => {
+ if ( timer !== undefined ) { return; }
+ let skip = true;
+ for ( let i = 0; i < mutations.length && skip; i++ ) {
+ const { type, addedNodes, removedNodes } = mutations[i];
+ if ( type === 'attributes' ) { skip = false; }
+ for ( let j = 0; j < addedNodes.length && skip; j++ ) {
+ if ( addedNodes[j].nodeType === 1 ) { skip = false; break; }
+ }
+ for ( let j = 0; j < removedNodes.length && skip; j++ ) {
+ if ( removedNodes[j].nodeType === 1 ) { skip = false; break; }
+ }
+ }
+ if ( skip ) { return; }
+ timer = self.requestIdleCallback(rmclass, { timeout: 67 });
+ };
+ const start = ( ) => {
  rmclass();
+ if ( /\bstay\b/.test(behavior) === false ) { return; }
+ const observer = new MutationObserver(mutationHandler);
+ observer.observe(document.documentElement, {
+ attributes: true,
+ attributeFilter: [ 'class' ],
+ childList: true,
+ subtree: true,
+ });
+ };
+ if ( document.readyState !== 'complete' && /\bcomplete\b/.test(behavior) ) {
+ self.addEventListener('load', start, { once: true });
+ } else if ( document.readyState === 'loading' ) {
+ self.addEventListener('DOMContentLoaded', start, { once: true });
+ } else {
+ start();
  }
 })();