TimeView has update2 method?

In https://github.com/jupyter-widgets/ipywidgets/pull/3618, @vidartf  remarks:

> The change itself looks good, and fixes an annoying bug! I think this bug is the reason that TimeView has an update2 method? > So that one can probably be changed back to use update then.

This issue is to keep track of looking into this.