Code review comment for lp:~tpeeters/ubuntu-ui-toolkit/fixPopoverPointer

Works very well. As agreed on IRC it's unfortunate we have no tests so bug 1317226 accounts for that. Manual testing is possible by either checking the popover example in the gallery on a phone, or making the window very small on the desktop, and observing the position of the arrow - it should stay on the bottom, without the fix is moves to the top.