Fix logic of caching display string positions for bidi display.

 src/xdisp.c (compute_display_string_pos): Fix logic of caching
 previous display string position.  Initialize cached_prev_pos to -1.
 Fixes slow-down at the beginning of a buffer.

diff --cc src/ChangeLog
index e537848ea412d8b051bfd27d510349100b8e07f1,8aa1237f6931748be5a7e96170bd9cf3a47a524b..b3d2f64bcc7059af76ea61d75ad44fa34c208c48
--- 1/src/ChangeLog
--- 2/src/ChangeLog
+++ b/src/ChangeLog
@@@ -1,18 -1,11 +1,24 @@@
 -2011-07-24  Eli Zaretskii  <eliz@gnu.org>
++2011-07-25  Eli Zaretskii  <eliz@gnu.org>
+ 
+       * xdisp.c (compute_display_string_pos): Fix logic of caching
+       previous display string position.  Initialize cached_prev_pos to
+       -1.  Fixes slow-down at the beginning of a buffer.
+ 
 +2011-07-24  Eli Zaretskii  <eliz@gnu.org>
 +
 +      * xfaces.c (check_lface_attrs) [HAVE_WINDOW_SYSTEM]: Allow `nil'
 +      for attrs[LFACE_FONTSET_INDEX].
 +
 +2011-07-23  Paul Eggert  <eggert@cs.ucla.edu>
 +
 +      * xml.c (parse_region): Remove unused local
 +      that was recently introduced.
 +
  2011-07-23  Eli Zaretskii  <eliz@gnu.org>
  
 +      * xfns.c (unwind_create_frame) [GLYPH_DEBUG]: Adapt to changes in
 +      2008-02-22T17:42:09Z!monnier@iro.umontreal.ca.
 +
        * xdisp.c (move_it_in_display_line_to): Record the best matching
        position for TO_CHARPOS while scanning the line, and restore it on
        exit if none of the characters scanned was an exact match.  Fixes

diff --cc src/xdisp.c
Simple merge