Historically it would return true for "at end" and false for "at start".
Change 282278 made this consistently return false, because at the time
empty stops could have indicated that the diff was still loading. This
is no longer the case, as it is now handled with an explicit AbortStop.
On the contrary, when gr-diff is configured to not render the file line,
fully loaded diffs empty, binary or image diffs would have empty stop,
and it makes more sense in this case to consider the cursor "at end"
e.g. for the purpose of showing an "tap x again to advance to next
file" toast.
Change-Id: I4c88e4ec47a1619e14081ba424d8056b754de125
2ac4609b92