bug#36347: 26.2.90; fontification mistakes contraction for a string in HTML

[Eli Zaretskii]

> From: Noam Postavsky <npostavs@gmail.com>
> Date: Sun, 23 Jun 2019 21:47:00 -0400
> Cc: 36347@debbugs.gnu.org
> 
> So the question is what to do about this for the release branch.
> 
> 1. Revert the fix which adds handling of single quotes.  This means
> single quotes never cause highlighting, even when they should.  This is
> a regression in nxml-mode relative to Emacs 25, but sgml-mode worked
> like that for a while already (in Emacs 26, nxml-mode was changed to
> rely on some of sgml-mode's code).
> 
> 2. Fix this bug with the patch below, it's fairly small and
> straightforward.  And also, can be disabled by setting
> syntax-ppss-table to nil in sgml-mode-hook.
> 
> 3. Do nothing (for 26.3, that is).

Let's do 2).  I'd also like to ask Mike to please apply the change
locally and run with it, so we collect as much experience with it
before RC as possible.

Thanks.