Fix T94122: Export to X3D Fails.

Fixes call to `create_derived_objects()` in x3d export.

rBa82c9e1e405c84b9 introduced a change in the signature and return value of
the `create_derived_objects()` utility. This change lead to failure of the x3d
export addon.

Reviewed By: mont29

Differential Revision: https://developer.blender.org/D13667