fix TextArea inputRef update event

[Arbalester]

Fixes #4072

Checklist

• Includes tests
• Update documentation

Changes proposed in this pull request:

TextArea should call updated inputRef prop with the current DOM element.

[palantirtech]

Thanks for your interest in palantir/blueprint, @Arbalester! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[adidahiya]

thanks @Arbalester

[trixn86]

@Arbalester

Why are the inputRefs compared as their string representations (prevProps.inputRef.toString() !== this.props.inputRef.toString()) and not simply by reference equality? Is this intended to prevent it from updating when the user did not correctly memorize the callback? Feels like a hack to be honest. And it is also not be the behaviour one would expect. Reacts built-in elements handle that differently (https://codesandbox.io/s/thirsty-panini-oc3uu?file=/src/App.js).In my opinion the developer using the ref is responsible for correctly memorizing his/her ref callbacks. If I wanted to console.log the ref on every render cycle I couldn't do it just because the code of my function stays the same even when it's a new function.

Any even more problematic: If you pass a ref created by the useRef() hook, it will always be equal as it's an object whose string representation is simply [object Object].

[Arbalester]

@Arbalester

Why are the inputRefs compared as their string representations (prevProps.inputRef.toString() !== this.props.inputRef.toString()) and not simply by reference equality? Is this intended to prevent it from updating when the user did not correctly memorize the callback? Feels like a hack to be honest. And it is also not be the behaviour one would expect. Reacts built-in elements handle that differently (https://codesandbox.io/s/thirsty-panini-oc3uu?file=/src/App.js).In my opinion the developer using the ref is responsible for correctly memorizing his/her ref callbacks. If I wanted to console.log the ref on every render cycle I couldn't do it just because the code of my function stays the same even when it's a new function.

Any even more problematic: If you pass a ref created by the useRef() hook, it will always be equal as it's an object whose string representation is simply [object Object].

Yeah, my bad. Made a fix for this.