fix: check intersectionRatio in addition to isIntersecting

[thebuilder]

This uses intersectionRatio to determine if a component is inView, instead of relying on `isIntersecting.

Closes #383

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[thebuilder]

🎉 This PR is included in version 8.28.3 🎉

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[szager-chromium]

Hello -- I'm the original implementer and spec editor of IntersectionObserver, and I recently stumbled across this issue.

This is indeed a subtle and thorny issue. I filed a bug in the spec repository a while back, but I've had difficulty getting traction for a proposed fix. It would be very helpful if the maintainer of a widely-used library which has encountered the problem could chime in...

w3c/IntersectionObserver#432

Thanks!

[thebuilder]

@szager-chromium could this issue also be related to #513 ?