Flat worlds don't have expanded build range

Note: I'm not sure if this is actually a bug as the change log didn't specify one way or the other.

 

Description: The title says it all

 

Steps to recrate:

1). Create a flat world

2). Attempt through any means to place a block outside the old build bounds but inside the new ones

 

Expected results: block places as it would in an infinite world

 

Observed results: block fails to place as it would before the bounds expansion