Try points one pixel into the elements from the edges

Try points one pixel into the elements from the edges

On newyorker.com, `transform: translate3d(0, 0, 0)` is applied on the
content container, to force hardware acceleration. It seems to move
everything a pixel, causing `document.elementFromPoint` to fail at the
edges of elements. This commit no longer looks exactly at the edges of
elements, but one pixel in, which seems to be a safer strategy. (The
marker is still nicely placed exactly on the edge, though.)

Example page:
http://www.newyorker.com/currency-tag/the-virtual-moleskine