bug#43218: EWW handles default answer incorrectly when changing a select

[Drew Adams <drew.adams@oracle.com>]

> > The point is that the `completing-read' behavior,
> > which shows only the car of an alist entry (plus
> > possibly an annotation), is quite limited.
> 
> Yeah.  And I now remember why the question seemed so familiar to me -- I
> think I asked the same question a couple a years ago when I wrote a mode
> for doing IMDB searches, and I ended up with (I see now; I'd forgotten
> all about this):...
> 
> But I guess I still wonder why `completing-read' strips the text
> properties from the completions?  If it's historical reasons, why
> not allow minibuffer-allow-text-properties to override that?

`completing-read' is likely older than text properties
on strings.  (It was coded only in C for a long time.)

As I said, `minibuffer-allow-text-properties' only has
an effect on text that is in the minibuffer.  When you
complete against candidates, the result may or may not
ever get put into the minibuffer, and it has no text
properties.