Remove re-positioning of boxes on snap-to-lines

Boxes are already positioned with x-position and y-position calculation
in step 8 when snapt-to-lines is true.
Closes https://www.w3.org/Bugs/Public/show_bug.cgi?id=19178
Merge pull request #100 from silviapfeiffer/snapToLinesPositioning

Remove re-positioning of boxes on snap-to-lines