As I understand this is a port of change from the core (specifically this one: https://gerrit.wikimedia.org/r/#/c/100490), but it seem to be missing a piece in here (compare with line 1133 in https://gerrit.wikimedia.org/r/#/c/100490/5/modules/ve/ce/ve.ce.Surface.js). If this is intentional please confirm, if not, please make sure that it is not missing some other parts of that change set as well.