reset() not finished on sync return

[jerch]

coming from #4319 (reply in thread) - the Terminal.reset call does not finish the re-initialization synchronous.

possible fixes:
Either make it a promise (rather a quickfix and with ugly API change), or revisit the code paths, that are not ready yet when returning synchronously from the method and execute them in sync.

[Tyriar]

This is surprising, it was always meant to be sync so hopefully we can fix it.

[Tyriar]

clear too? 😕 #4319 (reply in thread)

This isn't just a re-rendering problem is it?

[jerch]

This isn't just a re-rendering problem is it?

Haven't looked into it yet, I'd say yes - its a re-rendering issue with false scrollOffset from viewport.ts (prolly due to using an animation frame there, its just a guess though atm).

clear too?

Yeah, seems so.

[Tyriar]

Repro: run this in console term.reset(); term.write('1\n2\n3\n\r'.repeat(20));