WindowServer: Use early return to reduce nesting

Author: https://github.com/shannonbooth
Commit: 97508844dc
Pull-request: https://github.com/SerenityOS/serenity/pull/1209
Reviewed-by: https://github.com/awesomekling

Servers/WindowServer/Menu.cpp

@@ -125,8 +125,11 @@ void Menu::redraw()
 
 Window& Menu::ensure_menu_window()
 {
+    if (m_menu_window)
+        return *m_menu_window;
+
     int width = this->content_width();
-    if (!m_menu_window) {
+
     Gfx::Point next_item_location(frame_thickness(), frame_thickness());
     for (auto& item : m_items) {
         int height = 0;
@@ -151,7 +154,7 @@ Window& Menu::ensure_menu_window()
     window->set_rect(0, 0, width, window_height);
     m_menu_window = move(window);
     draw();
-    }
+
     return *m_menu_window;
 }