Revert the part of 945dda6e39da3828732b02860d6f663ae23e47f9 that is backwards incompatible.
Revert the part of 945dda6e39da3828732b02860d6f663ae23e47f9 that is backwards incompatible.

Since the change is a backwards-incompatible change in the spec, we’ll need to wait until we update the spec to make the change.

SylvainCorlay/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,jupyter-widgets/ipywidgets,jupyter-widgets/ipywidgets,jupyter-widgets/ipywidgets,SylvainCorlay/ipywidgets,SylvainCorlay/ipywidgets,jupyter-widgets/ipywidgets,SylvainCorlay/ipywidgets,ipython/ipywidgets