IME bug of the day: Sogou input doesn't trigger compositionend when hosting xterm in Electron 13.

Repro: yarn electron https://xtermjs.org.

The only usable event is input with .composed && .inputType == "insertText", but that is currently being ignored due to the Linux IME fix in #3533. I'm going to try to figure out a way to distinguish between these events, but it's possible that xterm is going to need a way for the user to indicate the platform it's running on, or some sort of a "quirks mode".

It's also possible that Sogou's internal "whitelist" doesn't recognize Electron 13 (microsoft/vscode#115814 (comment))