Change tests to make them pass on firefox

Editor assessment

The subject states both the change and its purpose: tests were adjusted so they pass on Firefox. That is fully understandable without the diff, and the fix type and curriculum scope are accurate for a test correction. No body appears, and one line on why the tests failed only in Firefox would have added teaching value, but the subject carries the essential fact for a small change. The PR reference is well formed and no footers add noise. Style is clean: imperative mood, no trailing period, sensible length, consistent language. Clear and honest, with only the untold browser quirk keeping it short of excellent.