Named widget-constructor table for §81's "UI controls" point.
Map preserves insertion order, which is the order names reports (§33).
Map
Registered names, in insertion order.
Number of registered controls.
The constructor for name, or undefined.
name
undefined
Whether name has a constructor.
Registers control under name. Returns this so registrations chain.
control
this
FourError INVALID_APPLICATION_STATE if name is empty, or if a different constructor already occupies that name.
INVALID_APPLICATION_STATE
Named widget-constructor table for §81's "UI controls" point.
Mappreserves insertion order, which is the order names reports (§33).