Add prevent-dialog scriptlet

@Scriptlet prevent-dialog

@description
Programmatically close `dialog` elements.

@param [selector]
Optional. The dialog element must matches `dialog{selector}` for the
prevention to take place.

@Usage:
example.com##+js(prevent-dialog)

Author: gorhill

src/js/resources/prevent-dialog.js

@@ -0,0 +1,72 @@
+/*******************************************************************************
+
+    uBlock Origin - a comprehensive, efficient content blocker
+    Copyright (C) 2025-present Raymond Hill
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see {http://www.gnu.org/licenses/}.
+
+    Home: https://github.com/gorhill/uBlock
+
+*/
+
+import { registerScriptlet } from './base.js';
+import { safeSelf } from './safe-self.js';
+
+/**
+ * @scriptlet prevent-dialog
+ * 
+ * @description
+ * Programmatically close `dialog` elements.
+ * 
+ * @param [selector]
+ * Optional. The dialog element must matches `dialog{selector}` for the
+ * prevention to take place.
+ * 
+ * @usage:
+ * example.com##+js(prevent-dialog)
+ * 
+ * */
+
+export function preventDialog(
+    selector = '',
+) {
+    const safe = safeSelf();
+    const logPrefix = safe.makeLogPrefix('prevent-dialog', selector);
+    const prevent = ( ) => {
+        debouncer = undefined;
+        const elems = document.querySelectorAll(`dialog${selector}`);
+        for ( const elem of elems ) {
+            if ( typeof elem.close !== 'function' ) { continue; }
+            if ( elem.open === false ) { continue; }
+            elem.close();
+            safe.uboLog(logPrefix, 'Closed');
+        }
+    };
+    let debouncer;
+    const observer = new MutationObserver(( ) => {
+        if ( debouncer !== undefined ) { return; }
+        debouncer = requestAnimationFrame(prevent);
+    });
+    observer.observe(document, {
+        attributes: true,
+        childList: true,
+        subtree: true,
+    });
+}
+registerScriptlet(preventDialog, {
+    name: 'prevent-dialog.js',
+    dependencies: [
+        safeSelf,
+    ],
+});

src/js/resources/scriptlets.js

@@ -27,6 +27,7 @@ import './json-edit.js';
 import './json-prune.js';
 import './noeval.js';
 import './object-prune.js';
+import './prevent-dialog.js';
 import './prevent-fetch.js';
 import './prevent-innerHTML.js';
 import './prevent-settimeout.js';