If a node that establishes a StackingContext has `pointer-events: none`,
hit testing should first proceed with hit testing the SC's children
before deciding to bail. We were checking for `pointer-events` too
early, causing large parts of certain websites to be noninteractive.
Fixes#6017.
Instead of ignoring any paintable immediately when they're invisible to
hit-testing, consider every candidate and while the most specific
candidate is invisible to hit-testing, traverse up to its parent
paintable.
This more closely reflects the behavior expected when wrapping block
elements inside inline elements, where although the block element might
have `pointer-events: none`, it still becomes part of the hit-test body
of the inline parent.
This makes the following link work as expected:
<a href="https://ladybird.org">
<div style="pointer-events: none">Ladybird</div>
</a>
