Auto merge of #23786 - Manishearth:xr-wpt, r=asajeffrey

Enable XR WPT tests

This enables the tests. Most still fail, I plan to go through the
failures more soon.

xrFrame_getPose's failure seems to indicate we have broken matrix math.
I'm not sure what, the bug seems to not come from a simple matrix
inversion/ordering mishap.

This does add empty stubs for session ending since the test infra relies on these existing for almost every test (https://github.com/servo/servo/issues/23788). We will need to add support for this from the webxr repo side. We also need to add support for user activation (https://github.com/servo/servo/issues/23787).

r? @asajeffrey

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components/script/dom/xrsession.rs

@@ -155,7 +155,7 @@ impl XRSession {
             }
         }
 
-        // Step 9: XXXManishearth unset `active` bool on `frame`
+        frame.set_active(false);
         self.session.borrow_mut().render_animation_frame();
 
         // If the canvas element is attached to the DOM, it is now dirty,
@@ -302,6 +302,14 @@ impl XRSessionMethods for XRSession {
             .map(|x| DomRoot::from_ref(&**x))
             .collect()
     }
+
+    /// https://immersive-web.github.io/webxr/#dom-xrsession-end
+    fn End(&self) -> Rc<Promise> {
+        // XXXManishearth implement device disconnection and session ending
+        let p = Promise::new(&self.global());
+        p.resolve_native(&());
+        p
+    }
 }
 
 #[derive(Clone, Copy, Debug)]