devas vg: return default root node if possible.

Summary:

It could return NULL root node
while user expect a valid root node in default
as It did before.

This is a regresion bug from long ago.

@fix

Reviewers: #committers

Subscribers: cedric, #reviewers, #committers

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D7162

src/lib/evas/canvas/efl_canvas_vg_object.c

@@ -130,6 +130,8 @@ _efl_canvas_vg_object_root_node_get(const Eo *obj EINA_UNUSED, Efl_Canvas_Vg_Obj
      root = evas_cache_vg_tree_get(pd->vg_entry);
    else if (pd->user_entry)
      root = pd->user_entry->root;
+   else
+     root = pd->root;
 
    return root;
 }