[pango] Fix backspacing for more Emoji sequences

[Matthias Clasen <matthiasc src gnome org>]

commit 7c5b158ce47ffef5be88694a3d12f3b38a784318
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Aug 17 00:01:41 2017 -0400

    Fix backspacing for more Emoji sequences
    
    Behdad pointed out that I didn't get it right for
    flags and for sequences ending in a skin tone modifier.
    
    Fix that.

 pango/break.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/pango/break.c b/pango/break.c
index f1bfb99..b92e768 100644
--- a/pango/break.c
+++ b/pango/break.c
@@ -869,7 +869,10 @@ pango_default_break (const gchar   *text,
             if (prev_GB_type == GB_E_Base ||
                 prev_GB_type == GB_E_Base_GAZ ||
                 prev_GB_type == GB_Glue_After_Zwj ||
-                prev_GB_type == GB_Extend)
+                prev_GB_type == GB_Extend ||
+                prev_GB_type == GB_E_Modifier ||
+                prev_GB_type == GB_RI_Odd ||
+                prev_GB_type == GB_RI_Even)
              attrs[i].backspace_deletes_character = FALSE;
             else
              attrs[i].backspace_deletes_character = BACKSPACE_DELETES_CHARACTER (base_character);