[gtk/layout-child-type] Add missing handler for <layout> elements in UI files

[Emmanuele Bassi <ebassi src gnome org>]

commit ecba428d52f52572705991c20fb430e55ea02116
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Mar 28 17:16:57 2019 +0000

    Add missing handler for <layout> elements in UI files
    
    The layout properties sub-parser needs to handle the parent tag.

 gtk/gtkwidget.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 509099addf..8b57fdf415 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -10134,6 +10134,16 @@ layout_start_element (GMarkupParseContext  *context,
 
       layout_data->cur_property = pinfo;
     }
+  else if (strcmp (element_name, "layout") == 0)
+    {
+      if (!_gtk_builder_check_parent (layout_data->builder, context, "object", error))
+        return;
+
+      if (!g_markup_collect_attributes (element_name, names, values, error,
+                                        G_MARKUP_COLLECT_INVALID, NULL, NULL,
+                                        G_MARKUP_COLLECT_INVALID))
+        _gtk_builder_prefix_error (layout_data->builder, context, error);
+    }
   else
     {
       _gtk_builder_error_unhandled_tag (layout_data->builder, context,