bug#41531: 27.0.91; Better handle asynchronous eldoc backends

[Dmitry Gutov]

On 08.07.2020 16:25, Stefan Monnier wrote:
> - do a quick version of the code for yourself.
> - then compare that with Joao's version.
> - then do a mix of:
>    - argue to change or remove some parts of his code (those that would
>      make it difficult for you to install your code on top of his)
>    - keep the other changes to apply them after he installs his

Since he went ahead, ignored the review and pushed the changes, 
apparently I can just do the same now.

That just leaves the buggy new features which went in without proper 
justification. Can I go ahead and remove them, then?