Auto merge of #23547 - Manishearth:reference-spaces, r=asajeffrey

Update to latest WebXR spec, add tests

This pulls in a bunch of the newer stuff. I think with this PR we're spec-compatible for the things we support.

<s>For testing I'm likely going to write custom tests rather than adapting the existing ones, as a first pass, but when I start adapting the existing ones these changes will make it smoother.</s>

This PR also adds some pretty simple tests that deal with core functionality.

r? @jdm @asajeffrey

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tests/wpt/mozilla/meta/MANIFEST.json

@@ -11222,7 +11222,10 @@
      {}
     ]
    ],
-   "mozilla/xmlhttprequest_url.html": []
+   "mozilla/xmlhttprequest_url.html": [],
+   "webxr/resources/webxr-util.js": [
+    []
+   ]
   },
   "testharness": {
    "bluetooth/advertisingEvent/watchAdvertisements-succeeds.html": [
@@ -13927,6 +13930,18 @@
      "mozilla/xmlhttprequest_url.html",
      {}
     ]
+   ],
+   "webxr/create_session.html": [
+    [
+     "webxr/create_session.html",
+     {}
+    ]
+   ],
+   "webxr/obtain_frame.html": [
+    [
+     "webxr/obtain_frame.html",
+     {}
+    ]
    ]
   },
   "visual": {
@@ -21112,6 +21127,18 @@
   "mozilla/xmlhttprequest_url.html": [
    "e5d10f27c06e1febd3bb70f8f128194fc3f63861",
    "testharness"
+  ],
+  "webxr/create_session.html": [
+   "306ab85d3b1b914d2dd7c11a3b03dccd990148ae",
+   "testharness"
+  ],
+  "webxr/obtain_frame.html": [
+   "1089bb25c2f6b26db4e21b6bf07c28add3fee5ec",
+   "testharness"
+  ],
+  "webxr/resources/webxr-util.js": [
+   "505173c82998a80b1e543f1a18aefaf1891f8269",
+   "support"
   ]
  },
  "url_base": "/_mozilla/",

tests/wpt/mozilla/meta/webxr/__dir__.ini

@@ -0,0 +1,2 @@
+prefs: [dom.webxr.enabled:true, dom.webxr.test:true]
+