bug#23610: 25.0.94; c++-mode doesn't fontify typename... like typename

[Ivan Andrus]

Starting with emacs -Q, Y is not fontified in the snippet below, whereas
X is.

-Ivan


template <typename X, typename... Y>
class bob {

};


In GNU Emacs 25.0.94.2 (x86_64-apple-darwin15.4.0, NS appkit-1404.46
Version 10.11.4 (Build 15E65))
of 2016-05-22 built on iandrus-osx
Repository revision: ae8352b8219b3d40f70fda8986ae86fbef7322fb
Windowing system distributor 'Apple', version 10.3.1404
Configured using:
'configure --with-ns --with-modules
PKG_CONFIG_PATH=/opt/X11/lib/pkgconfig'

Configured features:
JPEG RSVG IMAGEMAGICK DBUS NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS NS MODULES

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

Major mode: C++/l

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t
  abbrev-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
user-error: The mark is not set now, so there is no region
Undo!
<C-s-268632064> is undefined
user-error: The mark is not set now, so there is no region
user-error: No mark set in this buffer
Mark set
Undo!

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util help-fns mail-prsvr mail-utils
cl-extra help-mode cc-mode cc-fonts easymenu cc-guess cc-menus cc-cmds
cc-styles cc-align cc-engine cc-vars cc-defs cl-loaddefs pcase cl-lib
time-date mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel ns-win ucs-normalize term/common-win tool-bar dnd
fontset image regexp-opt fringe tabulated-list newcomment elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core 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 charscript
case-table epa-hook jka-cmpr-hook help simple abbrev 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 dbusbind kqueue cocoa
ns multi-tty make-network-process emacs)

Memory information:
((conses 16 216680 9514)
(symbols 48 22190 2)
(miscs 40 50 243)
(strings 32 20775 6226)
(string-bytes 1 712665)
(vectors 16 35464)
(vector-slots 8 687847 4136)
(floats 8 163 110)
(intervals 56 332 8)
(buffers 976 11))