[core] fix(InputGroup): async controlled updates

[adidahiya]

Alternative fix for issue described in #4262 and facebook/react#3926

Checklist

• Includes tests
• Update documentation

Changes proposed in this pull request:

Add a new private component, AsyncControllableInput, which works around the problems in the linked React issue, alleviating some bugs we've experienced with IME

Reviewers should focus on:

Test this in a real product and make sure it doesn't break anything

Screenshot

N/A

[blueprint-bot]

[core] fix(InputGroup): async controlled updates

Previews: documentation | landing | table

[rynorris]

@adidahiya I've tested this PR against the product where we originally found the issue, and it does appear to fix it.

However, unless I'm mistaken, we're still relying on the state update here being synchronous. In practice, given how small and simple this component is, it seems likely this state update will always be synchronous (hence why it appears to fix the issue), but I don't think that's guaranteed by React at all.

I'm not sure if there's a better fix though, and maybe we're ok with it just being significantly less vulnerable to the issue than before?

[blueprint-bot]

fix: pass down inputRef to input

Previews: documentation | landing | table

[adidahiya]

I tried fixing the tests but I don't see an obvious reason why they would fail only in React 15. I will come back to this later this week, but if you have any ideas I would welcome them in the meantime

[adidahiya]

🤦 I had forgot to apply the react-lifecycles-compat polyfill to make getDerivedStateFromProps work in React 15...

[blueprint-bot]

apply react-lifecycles-compat polyfill

Previews: documentation | landing | table