Add tab close icon to the default theme

scene/gui/tabs.cpp

@@ -708,7 +708,7 @@ void Tabs::add_tab(const String& p_str,const Ref<Texture>& p_icon) {
 	t.text=p_str;
 	t.icon=p_icon;
 
-	t.close_button = get_icon("Close","EditorIcons");
+	t.close_button = get_icon("close");
 
 	tabs.push_back(t);
 

scene/resources/default_theme/default_theme.cpp

@@ -717,6 +717,7 @@ void make_default_theme() {
 	t->set_icon("increment_hilite","Tabs",make_icon( scroll_button_right_hl_png));
 	t->set_icon("decrement","Tabs",make_icon( scroll_button_left_png));
 	t->set_icon("decrement_hilite","Tabs",make_icon( scroll_button_left_hl_png));
+	t->set_icon("close","Tabs",make_icon( tab_close_png));
 
 	t->set_font("font","Tabs", default_font );