Check ancestors overflow style instead of descendant's overflow style in IsVisible()

[DimiDL]

Emilio mentioned that the following code is wrong while review this patch

fathom/fathom/utilsForFrontend.mjs

Lines 502 to 506 in 49d678d

	if ((rect.width === 0 || rect.height === 0) && elementStyle.overflow === 'hidden') {
	// Zero-sized ancestors don’t make descendants hidden unless the descendant
	// has ``overflow: hidden``.
	return false;
	}

The overflow style of descendants doesn't affect whether they are visible in presence of a zero-sized ancestor. You want to check the overflow style of the ancestor itself if you want that.