Bug 1600445 - Update expectations for decode-utf8.any.serviceworker.html on release or beta. r=jgraham

Differential Revision: https://phabricator.services.mozilla.com/D55368

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

testing/web-platform/meta/encoding/streams/decode-utf8.any.js.ini

@@ -182,6 +182,10 @@
 
 
 [decode-utf8.any.serviceworker.html]
+  bug: 1600445
+  expected:
+    if release_or_beta: ERROR 
+
   [decoding one UTF-8 chunk should give one output string - SharedArrayBuffer]
     expected: FAIL