Current browser implementations seem to have serious appearance flaws, for example browser stylesheet appearance can't be unset, therefore putting on stalled.
Also created an OOUI Demos page:
Change 763709 abandoned by VolkerE:
[oojs/ui@master] Use progress element for ProgressBarWidget
Abandoned due to unclear path forward with current browser's styling limitations of native progress element. Recommend to reactivate patch later if browser support has changed.