bug#21881: 24.4; eww-submit is nil

[Pushpal Sidhu <psidhu.devel@gmail.com>]

Running "emacs -q" and using eww, I find that some buttons on some
websites cause the following to occur: http://pastebin.com/MtZhnr5e

To reproduce easily:
1. point eww to: https://dev.openwrt.org/log/trunk/
2. Select "Show full log messages"
3. Click on the "Update" button.

The above steps will cause a wrong-type-argument integer-or-marker-p nil
to be thrown. I haven't been able to try 24.5, but I don't think there
were any eww changes between 24.4 and 24.5 anyways (reading NEWS.24.5).

In GNU Emacs 24.4.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2015-10-21 on psidhu
Windowing system distributor `The X.Org Foundation', version 11.0.11501000
System Description:	Ubuntu 14.04.3 LTS

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=none
  locale-coding-system: utf-8-unix

Major mode: eww

Minor modes in effect:
  tooltip-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

Recent input:
<help-echo> M-x e w w <return> d e v . g a t e <backspace> 
<M-backspace> o p e n w r t . o r g / l o g / t r u 
n k <return> C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-n C-n C-n C-l C-n C-n C-n 
C-n C-n C-n C-n C-n C-n C-f <return> C-n C-n <return> 
M-x t o g <tab> d e <tab> e r <tab> <return> <return> 
C-x o M-x r e p o <tab> r <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Contacting host: dev.openwrt.org:80
find-coding-systems-region: Wrong type argument: integer-or-marker-p, nil
Debug on Error enabled globally
Entering debugger...
Making completion list...

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mailabbrev gmm-utils mailheader sendmail help-mode
debug cus-start cus-load gnutls network-stream starttls url-http tls
mail-parse rfc2231 rfc2047 rfc2045 ietf-drums url-gw url-cache url-auth
eww easymenu mm-url gnus gnus-ems nnheader mail-utils wid-edit
cl-loaddefs cl-lib url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf url-util url-parse auth-source eieio
byte-opt bytecomp byte-compile cconv eieio-core gnus-util mm-util
help-fns mail-prsvr password-cache url-vars mailcap shr browse-url
format-spec time-date tooltip electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt
fringe tabulated-list newcomment lisp-mode prog-mode register page
menu-bar rfn-eshadow timer select scroll-bar 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 dynamic-setting system-font-setting font-render-setting
move-toolbar gtk x-toolkit x multi-tty emacs)

Memory information:
((conses 16 194966 7365)
 (symbols 48 22812 0)
 (miscs 40 523 104)
 (strings 32 35129 6504)
 (string-bytes 1 1102698)
 (vectors 16 13572)
 (vector-slots 8 437328 5796)
 (floats 8 97 172)
 (intervals 56 5915 577)
 (buffers 960 17)
 (heap 1024 54132 2717))