The plugin detects new "virtual" rows by comparing the vertical offsets of each element designated to be equalized. New rows are established when back-to-back elements are detected as having different offsets.

wet-boew#9589 fixed a bug that prevented it from working properly on deeply-nested elements using the eqht-trgt class. How? By changing how offsets were detected into a calculation representing the viewport's vertical scroll position + each element's top offset relative to the viewport.

The new calculation logic worked fine for visible elements, but not on hidden (display: none;) ones. Why? Because hidden elements don't have a top viewport offset. So inconsistent offsets were getting used when comparing visible elements against hidden ones.

End result was that if a visible element was followed by a hidden one, the plugin would end the current row and establish a new one... even if a subsequent visible element was still on the old row. That caused mismatched equalization and potentially-broken float layouts.

This fixes it by modifying the row detection logic to exclude hidden elements (i.e. anything with an offsetHeight of 0).

Partially addresses wet-boew#9607.