monitor: refactor MonitorHandle to store dyn object

This also alters `VideoMode` to be a regular object and not reference
the `MonitorHandle`, since it's a static data.

Given that `VideoMode` set may change during runtime keeping the
reference as a some sort of validity may not be idea and propagating
errors when changing video mode could be more reliable.

src/platform_impl/web/web_sys/canvas.rs

@@ -27,7 +27,7 @@ use crate::event::{
     SurfaceSizeWriter, WindowEvent,
 };
 use crate::keyboard::{Key, KeyLocation, ModifiersState, PhysicalKey};
-use crate::platform_impl::Fullscreen;
+use crate::monitor::Fullscreen;
 use crate::window::{WindowAttributes, WindowId};
 
 #[allow(dead_code)]
@@ -149,13 +149,7 @@ impl Canvas {
         }
 
         if let Some(fullscreen) = attr.fullscreen {
-            fullscreen::request_fullscreen(
-                main_thread,
-                &window,
-                &document,
-                &canvas,
-                fullscreen.into(),
-            );
+            fullscreen::request_fullscreen(main_thread, &window, &document, &canvas, fullscreen);
         }
 
         if attr.active {