Bug 1568868 restore release_or_beta expectation metadata r=jgraham

This was removed in
https://hg.mozilla.org/mozilla-central/rev/dbb4eb578278#l445.1
but this commit expresses the same logic differently to avoid removal on
future updates.  https://hg.mozilla.org/mozilla-central/rev/203e09f37d1f

Differential Revision: https://phabricator.services.mozilla.com/D39421

--HG--
extra : moz-landing-system : lando

testing/web-platform/meta/webaudio/the-audio-api/the-mediaelementaudiosourcenode-interface/cors-check.https.html.ini

@@ -1,5 +1,7 @@
 [cors-check.https.html]
-  expected: ERROR
+  expected:
+    if release_or_beta: OK
+    ERROR
   [\n      Test if MediaElementAudioSourceNode works for cross-origin redirects with\n      "cors" request mode.\n    ]
     expected: FAIL