bug#22222: 24.4; eww ignores charset=utf-8 in text/plain

[Trent W. Buck]

In #emacs on Freenode, "snotglob" reported that

    When I open this doc with eww
    
https://raw.githubusercontent.com/howardabrams/pdx-emacs-hackers/master/workshops/keyboard-macros.org
    it appears that some apostrophes are shown as \342\200\231

I can reproduce his fault.
I'm using UTF-8 in all the places it can be used.

That URL has this header field:

    Content-Type: text/plain; charset=utf-8

While eww-render correctly extracts the charset,
it doesn't use it:

    (eww-display-raw)

compare:

    (eww-display-html charset url nil point)

I have not actually tested HEAD,
but the issue appears to be present from RTFS:

    http://git.savannah.gnu.org/cgit/emacs.git/tree/lisp/net/eww.el#n347






In GNU Emacs 24.4.1 (x86_64-pc-linux-gnu)
 of 2014-10-26 on trouble, modified by Debian
System Description:     Debian GNU/Linux 8.0 (jessie)

Configured using:
 `configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --build x86_64-linux-gnu --prefix=/usr --sharedstatedir=/var/lib
 --libexecdir=/usr/lib --localstatedir=/var/lib
 --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes
 
--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.4/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.4/site-lisp:/usr/share/emacs/site-lisp
 --with-x=no --without-gconf --without-gsettings 'CFLAGS=-g -O2
 -fstack-protector-strong -Wformat -Werror=format-security -Wall'
 CPPFLAGS=-D_FORTIFY_SOURCE=2 LDFLAGS=-Wl,-z,relro'

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

Major mode: Fundamental

Minor modes in effect:
  xterm-mouse-mode: t
  ido-everywhere: t
  savehist-mode: t
  icomplete-mode: t
  show-paren-mode: t
  delete-selection-mode: t
  tooltip-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
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:


Recent messages:
Loading /usr/share/emacs/site-lisp/magit/magit-install.el (source)...done
Loading /etc/emacs/site-start.d/50magit.el (source)...done
Loading /etc/emacs/site-start.d/50pylint.el (source)...
Loading pylint...done
Loading /etc/emacs/site-start.d/50pylint.el (source)...done
Loading /etc/emacs/site-start.d/50python-docutils.el (source)...done
Loading /etc/emacs/site-start.d/50w3m-el-snapshot.el (source)...done
Loading /etc/emacs/site-start.d/51debian-el.el (source)...done
Loading term/xterm...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Load-path shadows:
/usr/share/emacs/24.4/site-lisp/debian-startup hides 
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs/site-lisp/rst hides /usr/share/emacs/24.4/lisp/textmodes/rst
/usr/share/emacs24/site-lisp/dictionaries-common/ispell hides 
/usr/share/emacs/24.4/lisp/textmodes/ispell
/usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides 
/usr/share/emacs/24.4/lisp/textmodes/flyspell

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader xterm advice sendmail rfc2047 rfc2045
ietf-drums mm-util help-fns mail-prsvr mail-utils jka-compr edmacro
kmacro cl-loaddefs cl-lib disp-table xt-mouse ido savehist icomplete
time-date paren delsel saveplace debian-el debian-el-loaddefs w3m-load
pylint compile comint regexp-opt ansi-color ring tool-bar 50magit
emacs-goodies-el emacs-goodies-custom emacs-goodies-loaddefs easy-mmode
dpkg-dev-el dpkg-dev-el-loaddefs tooltip electric uniquify ediff-hook
vc-hooks lisp-float-type tabulated-list newcomment lisp-mode prog-mode
register page menu-bar rfn-eshadow timer select mouse jit-lock font-lock
syntax facemenu font-core frame cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
case-table epa-hook jka-cmpr-hook help simple abbrev minibuffer 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 make-network-process dbusbind
gfilenotify multi-tty emacs)

Memory information:
((conses 16 102548 4949)
 (symbols 48 19418 0)
 (miscs 40 41 71)
 (strings 32 25459 5386)
 (string-bytes 1 684956)
 (vectors 16 9215)
 (vector-slots 8 355333 14722)
 (floats 8 69 208)
 (intervals 56 261 0)
 (buffers 960 11)
 (heap 1024 8764 721))