* Flip the logic to first detect if we are dealing with an unmodified mesh
in editmode. And then if not, detect if we need a mapping or not.
* runtime.is_original is only valid for the bmesh wrapper. Rename it to clarify
that and only check it when the mesh is a bmesh wrapper.
* Remove MR_EXTRACT_MAPPED and instead check only for the existence of the
origindex arrays. Previously it would sometimes access those arrays without
MR_EXTRACT_MAPPED set, which according to a comment means they are invalid.
Differential Revision: https://developer.blender.org/D15676
b247588dc0