Sticky panel
Verify the behavior of the sticky panel. Use visual viewport to verify the behavior
(pinch to zoom page). Best to run with --debug=stickypanel flag.
Tests:
- Panel should stick only when it's active.
-
Top viewport offset should be taken into account (visible part of it) when
scrolling the window especially when partly or non-visible in the visual
viewport.
- Panel should stick to the bottom of the container when it's near end.