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

[Mike Kupfer]

To reproduce:

1. start emacs with -Q
2. Visit (C-x C-f) the attached file (foo.html).

When I do this with 26.2.90, the text starting with the apostrophe in
"doesn't", and ending at the end of file, is fontified as a string.

When I do this with 26.2-rc1, the text is fontified as I would expect
(HTML tags are in blue, everything else is in the default black or dark
gray).

environment	notable wins	notable lossage
Cinnamon	the screen locker is nice (view of the wallpaper, with the current date and time)	window placement strategy is weak flakey when run in a VirtualBox guest (fixed now?) accessories and extensions don't seem to be as robust as for other DEs (e.g., errors when updating or installing an applet on Debian 9; notes applet doesn't work well) Expo view makes it too easy to unminimize a window when switching to a different desktop uses GNOME apps (e.g., Terminal)

In GNU Emacs 26.2.90 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars)
 of 2019-06-23 built on alto
Windowing system distributor 'The X.Org Foundation', version 11.0.11902000
System Description:     Debian GNU/Linux 9.9 (stretch)

Recent messages:
Mark set [3 times]
Auto-saving...done
Saving file /home/kupfer/private_html/computers.html...
Wrote /home/kupfer/private_html/computers.html
When done with this frame, type C-x 5 0
GNU Emacs 26.2.90 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars) of 
2019-06-23
Quit
When done with this frame, type C-x 5 0
Quit
Mark saved where search started

Configured features:
XPM JPEG TIFF GIF PNG SOUND NOTIFY GNUTLS LIBXML2 FREETYPE LIBOTF XFT
ZLIB TOOLKIT_SCROLL_BARS LUCID X11 XDBE XIM THREADS

Important settings:
  value of $LC_TIME: C
  value of $LANG: en_US.utf8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  shell-dirtrack-mode: t
  delete-selection-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny format-spec rfc822 mml
mml-sec password-cache epa derived epg epg-config gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils dired-x dired dired-loaddefs add-log
skeleton misearch multi-isearch sgml-mode seq gv dom elec-pair server
noutline outline easy-mmode cc-mode cc-fonts cc-guess cc-menus cc-cmds
cc-styles cc-align cc-engine cc-vars cc-defs byte-opt bytecomp
byte-compile cconv shell pcomplete comint ansi-color ring xcscope
easymenu advice delsel vc cl-loaddefs cl-lib vc-dispatcher timeclock
mdk-hacks time-date mule-util tooltip eldoc electric uniquify ediff-hook
vc-hooks lisp-float-type mwheel term/x-win x-win term/common-win x-dnd
tool-bar dnd fontset image regexp-opt fringe tabulated-list replace
newcomment text-mode elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core term/tty-colors frame cl-generic
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote threads inotify
dynamic-setting font-render-setting x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 152389 9893)
 (symbols 48 26251 1)
 (miscs 40 136 313)
 (strings 32 47063 956)
 (string-bytes 1 1299530)
 (vectors 16 20032)
 (vector-slots 8 595254 13062)
 (floats 8 89 321)
 (intervals 56 1199 0)
 (buffers 992 17))