[invidio_proxy_mode.user.js] Support Abrowser

Fix personal-script load after javascript loading from the DOM,
reported by a Trisquel user in Abrowser.

scripts-greasemonkey/invidio_proxy_mode.user.js

@@ -18,7 +18,7 @@
 // @grant        none
 // ==/UserScript==
 
-(function proxyMode() {
+function proxyMode() {
     const consoleCSS = 'background: #000; color: #00FF00; padding: 0px 7px; border: 1px solid #00FF00; line-height: 16px;';
 
     // Set variables
@@ -42,4 +42,10 @@
         }
     }
     console.log("%cUSERSCRIPT | " + GM_info.script.name + " " + GM_info.script.version + " | successfully initialized", consoleCSS);
-})();
+}
+proxyMode();
+
+// Fix Abrowser
+window.addEventListener('load', () => {
+  proxyMode();
+});