bug#14717: 24.3.50; Info-try-follow-nearest-node misses some footnotes

[Juri Linkov <juri@jurta.org>]

> 0. emacs -Q
> 1. Type `C-h i m Elisp RET m Using Interactive RET TAB TAB TAB' to put
>    point on the left parent of the reference mark for footnote (1) in
>    this node.
> 2. Type RET, expecting to jump to the footnote, but instead:
> => user-error: No such node or anchor: It may be a string; its contents
> are a sequence of elements
>
> The following patch makes the footnote search and
> hence jumping to the footnote in that node succeed

Thanks, your patch correctly fixes the bug, I recommend to commit it.

BTW, if you are interested what I'm trying to do in bug#14670
where I renamed the text property of footnotes from `link' to `shr-url'
is to support shr-url links in Info.  The value of the text properly
`shr-url' is the target of the link.  The problem is how to address
a footnote?  Maybe add a function that finds a footnote.  But I'm afraid
that supporting an arbitrary function on the text properly `shr-url'
is too unsafe.  So `shr-url' should contain only a string.  The question
is in what format to specify a link to a footnote.  Currently it has
the value `t'.  Perhaps as a string it could contain a line number
of the footnote like "(elisp) Using Interactive (line 42)".