bug#28907: 26.0.90; [eww] some problems in input/textarea

[Katsumi Yamaoka]

On Fri, 17 Nov 2017 17:42:35 +0900, Katsumi Yamaoka wrote:
> Some generic editing commands, except for `undo', now almost work
> in input/textarea.  To try writing something in those fields, you
> can use the following two pages:

> <https://html.com/tags/input/#Code_Example>
> <https://html.com/tags/textarea/#Code_Example>

I've completed the `undo' feature used in eww's editable fields.
It supports undo/redo-switching and works just like Emacs's undo.
The last (hopefully) patch containing changelog entries is here:

<http://www.jpl.org/tmp/eww.el-20171213.patch>

I would like to apply it to the emacs trunk if it is acceptable.

Thanks.