Remove Skin::setupSkinUserCss call

Method only calls parent and the parent is no-op

Bug: T257990
Change-Id: I44675efc351f74ba38e7d86b03aca48c15e0573e

includes/SkinTimeless.php

@@ -29,13 +29,4 @@ class SkinTimeless extends SkinTemplate {
 		// Basic IE support without flexbox
 		$out->addStyle( $this->stylename . '/resources/IE9fixes.css', 'screen', 'IE' );
 	}
-
-	/**
-	 * Add CSS via ResourceLoader
-	 *
-	 * @param OutputPage $out
-	 */
-	public function setupSkinUserCss( OutputPage $out ) {
-		parent::setupSkinUserCss( $out );
-	}
 }