[gitg/gtksourceview-vapi] Revert "Update GtkSourceView dependency"

[Alberto Fanjul <albfan src gnome org>]

commit c2594d48020c59e28cf24551ec83a0bd565aa47d
Author: Alberto Fanjul <albertofanjul gmail com>
Date:   Mon Oct 28 23:34:54 2019 +0100

    Revert "Update GtkSourceView dependency"
    
    This reverts commit bdba5b756f199fe20d3c44ce7c6e09ac55417ce8.

 libgitg/gitg-diff-view-file-selectable.vala | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/libgitg/gitg-diff-view-file-selectable.vala b/libgitg/gitg-diff-view-file-selectable.vala
index 46673c6f..369d7ae6 100644
--- a/libgitg/gitg-diff-view-file-selectable.vala
+++ b/libgitg/gitg-diff-view-file-selectable.vala
@@ -54,7 +54,7 @@ class Gitg.DiffViewFileSelectable : Object
 
                buffer.get_start_iter(out iter);
 
-               while (buffer.forward_iter_to_source_mark(iter, d_selection_category))
+               while (buffer.forward_iter_to_source_mark(ref iter, d_selection_category))
                {
                        ret += iter.get_line();
                }
@@ -321,7 +321,7 @@ class Gitg.DiffViewFileSelectable : Object
 
                var buffer = source_view.buffer as Gtk.SourceBuffer;
 
-               if (!buffer.forward_iter_to_source_mark(iter, "header"))
+               if (!buffer.forward_iter_to_source_mark(ref iter, "header"))
                {
                        iter.forward_to_end();
                }
@@ -493,7 +493,7 @@ class Gitg.DiffViewFileSelectable : Object
                }
                else
                {
-                       something_selected = (buffer as Gtk.SourceBuffer).forward_iter_to_source_mark(iter, 
d_selection_category);
+                       something_selected = (buffer as Gtk.SourceBuffer).forward_iter_to_source_mark(ref 
iter, d_selection_category);
                }
 
                if (something_selected != has_selection)