b2d9716b4a
Previously the UV unwrapping handling for subsurf modifiers used `DerivedMesh`to implement the subdivision. Since we're trying to remove `DerivedMesh` in general, and since this just made use of the `Mesh` data anyway, it's relatively simple to remove it here. Combined with D15939, this makes it possible to remove more `DerivedMesh` code. Differential Revision: https://developer.blender.org/D16487