diff --git a/resources/skins.vector.js/dropdownMenus.js b/resources/skins.vector.js/dropdownMenus.js
index d38296584..151bfa2fc 100644
--- a/resources/skins.vector.js/dropdownMenus.js
+++ b/resources/skins.vector.js/dropdownMenus.js
@@ -123,8 +123,12 @@ function addPortletLinkHandler( item, data ) {
 
 	// assign variables after early return.
 	const link = item.querySelector( 'a' );
-	const $menu = $( item ).parents( '.vector-menu' );
-	const menuElement = $menu.length && $menu.get( 0 ) || null;
+	const menuElement = /** @type {HTMLElement} */(
+		item.closest( '.vector-menu' )
+	);
+	if ( !menuElement ) {
+		return;
+	}
 
 	if ( data.id ) {
 		iconElement = createIconElement( menuElement, link, data.id );
@@ -132,7 +136,7 @@ function addPortletLinkHandler( item, data ) {
 
 	// The views menu has limited space so we need to decide whether there is space
 	// to accommodate the new item and if not to redirect to the more dropdown.
-	if ( $menu.prop( 'id' ) === 'p-views' ) {
+	if ( menuElement.id === 'p-views' ) {
 		const availableWidth = getAvailableViewMenuWidth();
 		const moreDropdown = document.querySelector( '#p-cactions ul' );
 
@@ -143,8 +147,7 @@ function addPortletLinkHandler( item, data ) {
 		}
 	}
 
-	// Check link.prepend exists for older browser since this is ES5 code
-	if ( link && iconElement && link.prepend ) {
+	if ( link && iconElement ) {
 		link.prepend( iconElement );
 	}
 }
diff --git a/resources/skins.vector.js/limitedWidthToggle.js b/resources/skins.vector.js/limitedWidthToggle.js
index 3267f2bc5..8dd0353d1 100644
--- a/resources/skins.vector.js/limitedWidthToggle.js
+++ b/resources/skins.vector.js/limitedWidthToggle.js
@@ -24,16 +24,7 @@ function init() {
 	toggle.addEventListener( 'click', function () {
 		features.toggle( LIMITED_WIDTH_FEATURE_NAME );
 		setDataAttribute( toggle );
-		// Fire a simulated window resize event (T328121)
-		let event;
-		if ( typeof Event === 'function' ) {
-			event = new Event( 'resize' );
-		} else {
-			// IE11
-			event = window.document.createEvent( 'UIEvents' );
-			event.initUIEvent( 'resize', true, false, window, 0 );
-		}
-		window.dispatchEvent( event );
+		window.dispatchEvent( new Event( 'resize' ) );
 	} );
 }
 
diff --git a/resources/skins.vector.js/menuTabs.js b/resources/skins.vector.js/menuTabs.js
index f57029a04..d5651fee8 100644
--- a/resources/skins.vector.js/menuTabs.js
+++ b/resources/skins.vector.js/menuTabs.js
@@ -14,11 +14,6 @@ function addNoIconClass( item ) {
 }
 
 function init() {
-	// Feature detect whether the `.closest` api is supported. If not, return early.
-	if ( !document.body.closest ) {
-		return;
-	}
-
 	// Enhance previously added items.
 	Array.prototype.forEach.call(
 		document.querySelectorAll( TABS_SELECTOR + ' ' + LIST_ITEM_JS_SELECTOR ),