support for pdf.js

The minimal example

\documentclass{article}
\usepackage{animate}

\begin{document}
\begin{animateinline}[controls]{1}
  \multiframe{10}{i=0+1}{\fbox{\Huge\i}}
\end{animateinline}
\end{document}

generates test4.pdf which works fine in Adobe Reader but not in Firefox's pdf.js viewer. According to the firefox issue tracker, PDF javascript has been supported since March 2021. Presumably the issue is related to the warnings I see in the console:

Warning: Push buttons without action dictionaries are not supported

and

ReferenceError: a0_playPauseFwd is not defined

when I click one of the buttons.

Presumably the warning at least is easy to fix by giving the button an "action dictionary" / routing the events through button actions?