Revert "Optimization: simplify fill_surfaces before the offset operation"
Revert "Optimization: simplify fill_surfaces before the offset operation"

To workaround issue #1325 and possibly #1320.

This reverts commit 3a046e34111aeaf3701062f006e9f5957635e15b.

platsch/Slic3r,xoan/Slic3r,mcilhargey/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,prusa3d/Slic3r,platsch/Slic3r,platsch/Slic3r,alexrj/Slic3r,tmotl/Slic3r,pieis2pi/Slic3r,xoan/Slic3r,mcilhargey/Slic3r,platsch/Slic3r,mcilhargey/Slic3r,mcilhargey/Slic3r,lordofhyphens/Slic3r,tmotl/Slic3r,alexrj/Slic3r,mcilhargey/Slic3r,alexrj/Slic3r,platsch/Slic3r,alexrj/Slic3r,platsch/Slic3r,prusa3d/Slic3r,lordofhyphens/Slic3r,pieis2pi/Slic3r,mcilhargey/Slic3r,alexrj/Slic3r,lordofhyphens/Slic3r,pieis2pi/Slic3r,prusa3d/Slic3r,curieos/Slic3r,tmotl/Slic3r,curieos/Slic3r,prusa3d/Slic3r,alexrj/Slic3r,curieos/Slic3r,mcilhargey/Slic3r,xoan/Slic3r,lordofhyphens/Slic3r,prusa3d/Slic3r,tmotl/Slic3r,curieos/Slic3r,curieos/Slic3r,tmotl/Slic3r,xoan/Slic3r,xoan/Slic3r,prusa3d/Slic3r,lordofhyphens/Slic3r,lordofhyphens/Slic3r,pieis2pi/Slic3r,tmotl/Slic3r,xoan/Slic3r,prusa3d/Slic3r,pieis2pi/Slic3r