Bug 1627379 - disable test_unregister_invalid_json.js on Win_QR for frequent failures. r=intermittent-reviewers,MasterWayZ DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D127791

dom/push/test/xpcshell/xpcshell.ini

@@ -48,6 +48,8 @@ run-sequentially = This will delete all existing push subscriptions.
 [test_unregister_empty_scope.js]
 [test_unregister_error.js]
 [test_unregister_invalid_json.js]
+skip-if =
+  os == "win" && webrender # Bug 1627379
 [test_unregister_not_found.js]
 [test_unregister_success.js]
 [test_updateRecordNoEncryptionKeys_ws.js]