- Properly convert coordinates for iframes with non-zero borders.
- IFrames that have `transform` anywhere in the ancestors skip
`hitPoint`-based check because we cannot reliably translate the viewport
point into frame document's coordinates.
Fixes#18245.
Although Playwright selectors do not pierce closed shadow roots,
one can still obtain a reference to an element inside a closed shadow root:
- through `page.evaluate()`;
- through `handle.$()` where `handle` is inside the shadow root;
- through `frame.locator()` by choosing an iframe that belongs
to a closed shadow root.
In this case, `click()` action fails during the hit check test,
but it's possible to make it work by going bottom up from the target
rather than top down from the document.
When target element is inside a non-main frame, there could be an
overlay in some of the parent frames that intercepts pointer events.
However, we never detected this case.
This restores the old hit target check, in addition to the new
hit target interceptor.
This way, we got some coverage for iframes and other quirky cases,
but keep the bullet-proof hit target check in place.
