[core] fix(OverflowList): edge case in shouldComponentUpdate

[braeden]

Checklist

• Includes tests
• Update documentation

Changes proposed in this pull request (update):

• Ensure we compare props reference equality in addition to the existing logic to ensure a re-render when props change. This is an addition to the logic introduced here: [OverflowList] Always re-render items #3278.

Context:

Through some testing, I've been able to repro the problematic condition: props change on the same tick as both state !== prevState AND shallowCompare(state, prevState) === true.

This means a re-render doesn't happen when it should. The original code was written to aggressively re-render (even in the case that the state doesn't change). But it failed to account for the case where: props change, state changes, but shallow compare is truthy (all in a single shouldComponentUpdate).

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Here's a log demonstrating this happen:

 console.log("SCU called! [props, state, shallowCompare, return]", this.props === _nextProps, this.state === nextState, shallowCompareKeys(this.state, nextState), !(this.state !== nextState && shallowCompareKeys(this.state, nextState)));

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Note: This component is reasonable suited returning to a PureComponent in the future, but that will be a breaking change.

[palantirtech]

Thanks for your interest in palantir/blueprint, @braeden! 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.