display: Add accessor function for ignored_modifier_mask

Some modifiers like NumLock and ScrollLock don't make sense in
keybindings, which is why we ignore them when matching keybindings
to events. We should do the same in Javascript, so add an accessor
function.

https://bugzilla.gnome.org/show_bug.cgi?id=665215

src/core/display.c

@@ -1406,6 +1406,19 @@ meta_display_get_current_time_roundtrip (MetaDisplay *display)
   return timestamp;
 }
 
+/**
+ * meta_display_get_ignored_modifier_mask:
+ * @display: a #MetaDisplay
+ *
+ * Returns: a mask of modifiers that should be ignored
+ *          when matching keybindings to events
+ */
+unsigned int
+meta_display_get_ignored_modifier_mask (MetaDisplay *display)
+{
+  return display->ignored_modifier_mask;
+}
+
 /**
  * meta_display_add_ignored_crossing_serial:
  * @display: a #MetaDisplay

src/meta/display.h

@@ -91,6 +91,8 @@ guint32 meta_display_get_last_user_time (MetaDisplay *display);
 guint32 meta_display_get_current_time (MetaDisplay *display);
 guint32 meta_display_get_current_time_roundtrip (MetaDisplay *display);
 
+unsigned int meta_display_get_ignored_modifier_mask (MetaDisplay  *display);
+
 GList* meta_display_get_tab_list (MetaDisplay   *display,
                                   MetaTabList    type,
                                   MetaScreen    *screen,