[gnome-terminal/gnome-3-22] search provider: Fix incorrect assumption

[Christian Persch <chpe src gnome org>]

commit ca5b8690b158f380e3bb37cf421199c05218e0e5
Author: Christian Persch <chpe gnome org>
Date:   Sun Nov 27 20:08:39 2016 +0100

    search provider: Fix incorrect assumption
    
    Not every application window is a TerminalWindow.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1398958`
    (cherry picked from commit 777e66d2b760704c4867997cc4049e54cb47163a)

 src/terminal-search-provider.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/src/terminal-search-provider.c b/src/terminal-search-provider.c
index 2e81dee..90c063e 100644
--- a/src/terminal-search-provider.c
+++ b/src/terminal-search-provider.c
@@ -119,9 +119,12 @@ handle_get_initial_result_set_cb (TerminalSearchProvider2  *skeleton,
   windows = gtk_application_get_windows (GTK_APPLICATION (app));
   for (l = windows; l != NULL; l = l->next)
     {
-      TerminalWindow *window = TERMINAL_WINDOW (l->data);
+      TerminalWindow *window = (TerminalWindow*)(l->data);
       GList *c, *containers;
 
+      if (!TERMINAL_IS_WINDOW (l->data))
+        continue;
+
       containers = terminal_window_list_screen_containers (window);
       for (c = containers; c != NULL; c = c->next)
         {