This way it is possible to have viewport simplification bumped all the way up,
making viewport really responsive but still have final render to use highest
subdivision possible.
Reviewers: lukastoenne, campbellbarton, dingto
Reviewed By: campbellbarton, dingto
Subscribers: dingto, nutel, eyecandy, venomgfx
Differential Revision: https://developer.blender.org/D1273