Bug 1720643 be consistent about using origin to separate subtest descriptions r=johannh DONTBUILD

The sandbox attribute recognizes a specific set of tokens.
https://html.spec.whatwg.org/multipage/iframe-embed-object.html#attr-iframe-sandbox

Differential Revision: https://phabricator.services.mozilla.com/D120063

dom/media/webrtc/tests/mochitests/test_getUserMedia_permission.html

@@ -59,8 +59,8 @@ runTest(async () => {
     const src = origin + path;
     is(await iframeGum({ src, sandbox: "allow-scripts" }),
        "NotAllowedError", "gUM fails in sandboxed iframe " + origin);
-    is(await iframeGum({ src, sandbox: "allow-scripts allow-same-origin " + origin }),
-       "success", "gUM works in regular iframe");
+    is(await iframeGum({ src, sandbox: "allow-scripts allow-same-origin" }),
+       "success", "gUM works in regular iframe" + origin);
   }
 
   // Test gUM in sandboxed vs regular srcdoc iframe