Auto merge of #24777 - servo:jdm-patch-34, r=Manishearth

Enable webxr by default

This changes two things:
* enable WebXR by default, since it's not exactly an experimental technology in Servo anymore
* enable the glwindow webxr backend by default so it's easier to test WebXR on desktop nightlies

Since the glwindow pref is only checked in the glutin desktop port, enabling it for other ports does not hurt us at all and it removes a papercut for testing WebXR content on desktop.

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tests/wpt/metadata/webvr/__dir__.ini

@@ -1 +1 @@
-prefs: ["dom.gamepad.enabled:true", "dom.webvr.enabled:true"]
+prefs: ["dom.gamepad.enabled:true", "dom.webvr.enabled:true", "dom.webxr.enabled:false"]

tests/wpt/mozilla/meta/MANIFEST.json

@@ -19023,7 +19023,7 @@
    "testharness"
   ],
   "mozilla/interfaces.html": [
-   "f1d58732adafef4afc9f9b7f16d6961e4b74a5e9",
+   "08e8181e6e639caeaecd84c16d582c0ec3f99474",
    "testharness"
   ],
   "mozilla/interfaces.js": [

tests/wpt/mozilla/tests/mozilla/interfaces.html

@@ -259,6 +259,22 @@ test_interfaces([
   "XMLHttpRequestEventTarget",
   "XMLHttpRequestUpload",
   "XMLSerializer",
+  "XR",
+  "XRFrame",
+  "XRInputSource",
+  "XRInputSourceArray",
+  "XRInputSourceEvent",
+  "XRPose",
+  "XRReferenceSpace",
+  "XRRenderState",
+  "XRRigidTransform",
+  "XRSession",
+  "XRSessionEvent",
+  "XRSpace",
+  "XRView",
+  "XRViewerPose",
+  "XRViewport",
+  "XRWebGLLayer",
   "console",
 ]);
 </script>

tests/wpt/webgl/meta/conformance/context/methods.html.ini

@@ -2,4 +2,7 @@
   bug: https://github.com/servo/servo/issues/15266
   [WebGL test #0: Property either does not exist or is not a function: isContextLost]
     expected: FAIL
-
+  [WebGL test #1: Also found the following extra methods:]
+    expected: FAIL
+  [WebGL test #2: makeXRCompatible]
+    expected: FAIL