Code review comment for lp:~bregma/unity/lp-1100120

This should probably be tested some, but I found the following to work:

- nux::Geometry geo_border(content_geo.x, content_geo.y, larger_absolute_geo.width - content_geo.x, larger_absolute_geo.height - content_geo.y + excess_border);
+ nux::Geometry geo_border(content_geo.x, content_geo.y, larger_absolute_geo.width - content_geo.x, larger_absolute_geo.height);