Fix report details summary in Firefox. (#20208)
Summary of the issue:
In focus mode in Mozilla Firefox, when a control which is not editable text is focused (such as a button), pressing NVDA+d to report the details summary reports "no additional details". In contrast, this works in Chromium browsers.
Description of user facing changes:
In Mozilla Firefox, reporting annotation details now works correctly in focus mode on controls which are not editable text.
Description of development approach:
script_reportDetailsSummary had some incorrect assumptions and contained code that was intended to execute but never did (effectively dead code). It assumed that browsers always set the caret even for non-editable controls, but that isn't always true, especially in Firefox. Even though it had code to fall back to using the focus, it returned early before that was ever executed. This change ensures that the fallback code actually runs, as well as fixing the fallback code so that it actually works.
I originally submitted this change as part of #20132, but that had to be reverted. This PR splits out just the details change.
