bug#26978: 25.2; incomplete display of SVG image

[ynyaaa@gmail.com]

(1)Texts in SVG are not displayed.
This sample should show "ABC" in a red square,
but three rectangles are displayed instead of "ABC".

<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100">
  <rect fill="red" width="100" height="100"/>
  <text x="10" y="60" font-size="40" fill="white">ABC</text>
</svg>

(2)External image files may not be displayed.
Copy emacs-25.2/share/icons/hicolor/16x16/apps/emacs.png
into the same directory of the sample SVG,
I can view the scaled emacs icon over a blue square with image-mode.

If emacs.png and the SVG are saved in the root directory,
viewing the SVG shows only a blue square.

If emacs.png is not in the same directory of the SVG nor its descendant
and the path of xlink:href="..." is rewritten,
viewing the SVG shows only a blue square.

If the current buffer is not related to any file
(i.e. buffer-file-name is nil),
evaluating (insert-image (create-image data-string 'svg t))
shows only a blue square.

<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100"
     xmlns:xlink="http://www.w3.org/1999/xlink">
  <rect fill="blue" width="100" height="100"/>
  <image xlink:href="emacs.png" width="100" height="100"/>
</svg>


I obtained librsvg-2.40.1-2-w32-bin.zip
from http://sourceforge.net/projects/ezwinports/files/.



In GNU Emacs 25.2.1 (i686-w64-mingw32)
 of 2017-04-25 built on LAPHROAIG
Windowing system distributor 'Microsoft Corp.', version 6.0.6002
Configured using:
 'configure --host=i686-w64-mingw32 --without-dbus
 --without-compress-install 'CFLAGS=-static -O2 -g3''

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS

Important settings:
  value of $LANG: JPN
  locale-coding-system: cp932

Major mode: Lisp Interaction

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

Recent messages:

Load-path shadows:
None found.

Features:
(pp 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 help-mode easymenu
cl-loaddefs pcase cl-lib mail-prsvr mail-utils time-date mule-util
japan-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel dos-w32 ls-lisp disp-table w32-win w32-vars
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
w32notify w32 multi-tty make-network-process emacs)

Memory information:
((conses 8 91787 12015)
 (symbols 32 19674 0)
 (miscs 32 58 179)
 (strings 16 15897 3822)
 (string-bytes 1 428454)
 (vectors 8 13073)
 (vector-slots 4 518142 10014)
 (floats 8 166 59)
 (intervals 28 219 37)
 (buffers 520 20))