fix: update dom traversal logic to also take the current element's visibility
fix: update dom traversal logic to also take the current element's visibility

In one scenario, the parent's `display` was set to `contents` which was causing the `offsetParent` and other related display fields to evaluate to not being visible.

This change checks for both the parent and current element visbility.

Fixes #78

GoogleChromeLabs/form-troubleshooter,GoogleChromeLabs/form-troubleshooter,GoogleChromeLabs/form-troubleshooter,GoogleChromeLabs/form-troubleshooter