bug#22749: 25.0.91; xwidget-webkit-scroll-down not working

[felix . dick]

In GNU Emacs 25.0.91.13 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.7)
 of 2016-02-18 built on acer
Repository revision: 3722a694fa094f88f7dfe54ccce7ea7cbaab214a
Windowing system distributor 'The X.Org Foundation', version 11.0.11801000
Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man
 --pdfdir=/usr/share/doc/emacs/pdf --with-sound=alsa --without-gconf
 --with-x-toolkit=gtk3 --with-xft --with-xwidgets 'CFLAGS=-march=x86-64
 -mtune=generic -O2 -pipe -fstack-protector-strong'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11 XWIDGETS

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

Major mode: Fundamental

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
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
previous-line: Beginning of buffer [15 times]
Undo! [4 times]
Making completion list...
Quit
Auto-saving...done
Undo! [2 times]
Redo! [4 times]
Undo! [6 times]
user-error: No further undo information [19 times]
next-line: End of buffer [16 times]
previous-line: Beginning of buffer [18 times]

Load-path shadows:
None found.

Features:
(pp shadow sort mail-extr emacsbug message idna dired format-spec rfc822
mml mml-sec 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 help-mode easymenu cl-loaddefs pcase
cl-lib mail-prsvr mail-utils time-date mule-util tooltip eldoc electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel x-win
term/common-win x-dnd 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 inotify dynamic-setting system-font-setting font-render-setting
xwidget-internal move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 90927 14936)
 (symbols 48 19847 0)
 (miscs 40 88 146)
 (strings 32 14562 4565)
 (string-bytes 1 417218)
 (vectors 16 12418)
 (vector-slots 8 430736 7611)
 (floats 8 167 201)
 (intervals 56 471 20)
 (buffers 976 14)
 (heap 1024 22424 1965))


with 'xwidget-webkit-scroll-behavior set to 'native',
xwidget-webkit-scroll-down gives the error message:

xwidget-webkit-scroll-down: Wrong type argument: wholenump, -50