Made highlighted item in PopupMenu circle back to the beginning/end when using the keyboard.

scene/gui/popup_menu.cpp

@@ -202,7 +202,11 @@ void PopupMenu::_gui_input(const Ref<InputEvent> &p_event) {
 
 			case KEY_DOWN: {
 
-				for (int i = mouse_over + 1; i < items.size(); i++) {
+				int search_from = mouse_over + 1;
+				if (search_from >= items.size())
+					search_from = 0;
+
+				for (int i = search_from; i < items.size(); i++) {
 
 					if (i < 0 || i >= items.size())
 						continue;
@@ -222,7 +226,11 @@ void PopupMenu::_gui_input(const Ref<InputEvent> &p_event) {
 			} break;
 			case KEY_UP: {
 
-				for (int i = mouse_over - 1; i >= 0; i--) {
+				int search_from = mouse_over - 1;
+				if (search_from < 0)
+					search_from = items.size() - 1;
+
+				for (int i = search_from; i >= 0; i--) {
 
 					if (i < 0 || i >= items.size())
 						continue;