Auto merge of #18024 - bradwerth:mediatypeAtom, r=emilio

Rework MediaType to be an atom-based struct instead of an enum.

MozReview-Commit-ID: 1Tfrs9PBkhA

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https://bugzilla.mozilla.org/show_bug.cgi?id=1371395
https://reviewboard.mozilla.org/r/163194/

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components/script/dom/mediaquerylist.rs

@@ -77,7 +77,7 @@ impl MediaQueryList {
         if let Some(window_size) = self.document.window().window_size() {
             let viewport_size = window_size.initial_viewport;
             let device_pixel_ratio = window_size.device_pixel_ratio;
-            let device = Device::new(MediaType::Screen, viewport_size, device_pixel_ratio);
+            let device = Device::new(MediaType::screen(), viewport_size, device_pixel_ratio);
             self.media_query_list.evaluate(&device, self.document.quirks_mode())
         } else {
             false