According to <https://github.com/fuweichin/xhtml5-esm-support>, an
internal script (a <script> element with content) can't be a module in
an XHTML page in Safari. So following the suggestion on that page, I
make the <script> on the page into a classic script, and use import()
to load the module containing the bedstead executable. Maybe this
will work on a reasonable selection of modern browsers.
Programs compiled with Emscripten end up statically linked against the
Emscripten runtime, which includes musl libc. So we need to comply with
their licences by including a copy of the licence and the relevant
copyright notices. I think putting them on the webstead page in small
print is probably the best approach.
This might need updating each release to match the version of Emscripten
that I build the editor with.
Apparently Chromium can't cope with "defer" scripts (which modules are
by default) in XHTML documents. But "async" scripts work properly,
so now we use one of those and then wait for DOMContentLoaded as
necessary.
