Remove incorrect poll method from object.instance_offset_from_cursor

Remove poll method from the `OBJECT_OT_instance_offset_from_cursor`
operator. It was checking for `context.active_object`, but not even doing
anything with the active object. It'll get in the way of exposing this
operator in another area of the interface, though.

release/scripts/startup/bl_operators/object.py

@@ -848,10 +848,6 @@ class DupliOffsetFromCursor(Operator):
     bl_label = "Set Offset from Cursor"
     bl_options = {'INTERNAL', 'UNDO'}
 
-    @classmethod
-    def poll(cls, context):
-        return (context.active_object is not None)
-
     def execute(self, context):
         scene = context.scene
         collection = context.collection