Auto merge of #24249 - ferjm:exit.fullscreen, r=paulrouget

Go back to original window size after exiting fullscreen

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #24200

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ports/glutin/headed_window.rs

@@ -325,7 +325,7 @@ impl WindowPortsMethods for Window {
     fn set_fullscreen(&self, state: bool) {
         if self.fullscreen.get() != state {
             self.gl_context.borrow_mut().window()
-                .set_fullscreen(Some(self.primary_monitor.clone()));
+                .set_fullscreen(if state { Some(self.primary_monitor.clone()) } else { None });
         }
         self.fullscreen.set(state);
     }