[Jellyfin] Old browsers

[dmitrylyzo]

This PR improves compatibility with older browsers.
Jellyfin is focused on supporting webOS 1.2 and Tizen 2.3, which use ancient web engines (WebKit).

I cherry-picked related commits, skipping merge-commits.

List of commits

82822b2
6444522
9299074
Merge pull request #15 from JustAMan/update-build
other commits are new

[TheOneric]

Thanks for your PRs! Assuming you spot-checled this PR doesn't break anything with JSO's example suit (the gh_pages branch); just a few nits:

Normally I'd like to see fixups done by amending the faulty/outdated patch-commit rather than adding yet another commit; howver since this is porting from JustAMan's jellyfin patches there's some value in keeping the commits as unchanged as possible. But your last two Remove unnecessary flags (already in GLOBAL_CFLAGS) and Remove deprecated flag (PR review) commits should imho be squashed into one Drop superfluous and deprecated flags commit.
Also it would be nice if you could add Cherry-pciked from: https://github.com/jellyfin/JavascriptSubtitlesOctopus/commit/<commit-hash> to the description of the cherry-picked commits.

---

If you haven't yet checked the examples: In order to test your changes, checkout the gh_pages branch in a seperate folder; update the assets/jsfolder to what building your PR yields and run a local server. Eg create a symlink named JavascriptSubtitlesOctopus in and to the root folder of the gh_pages repo and run this Python script: run-server.py. Your tests will be available at http://localhost:8000/JavscriptSubtitlesOctopus

You'll want to at least play the Video.JS sample until 01:10 and skip a bit through the Railgun S Karaoke Test, Attack on Titan Stress Karaoke Test and the Brotli Compressed Subtitle File examples and make sure the subtitles are rendered and not obviously borked.

[dmitrylyzo]

Done. Also, simplified from polyfills a bit.

Tested Video.JS, Railgun S Karaoke Test, Attack on Titan Stress Karaoke Test and Brotli Compressed Subtitle File - no issues except these errors in the console (the same for the JSO master):

Fontconfig error occurs when cache is disabled.

All these polyfills should probably be fixed in emscripten itself (emscripten-core/emscripten#11008 and emscripten-core/emscripten#11011)

[TheOneric]

Thanks again!
Looks good afaict and since Thiago also already approved, I'll merge it shortly.

no issues except these errors in the console (the same for the JSO master)

Yeah, the MIMe and following “ArrayBuffer instatiation” can be safely ignored, they are only because the test server setup doesn't know about the wasm-MIME type (and emscripten will fall back to fetching it anyway via “ArrayBuffer instatiation”) and well we don't have a favicon either. Not sure about the Fontconfig error, but it's not a regression and iinm will degrade font-lookup performance, but not break anything.

All these polyfills should probably be fixed in emscripten itself (emscripten-core/emscripten#11008 and emscripten-core/emscripten#11011)

Having emscripten provide the necessary polyfills would indeed be ideal.