Expose NOTIFICATION_POST_ENTER_TREE

(cherry picked from commit 677796a2c342ca221918e8dfa8d2361ae78082d1)

doc/classes/Node.xml

@@ -925,6 +925,9 @@
 		<constant name="NOTIFICATION_INTERNAL_PHYSICS_PROCESS" value="26">
 			Notification received every frame when the internal physics process flag is set (see [method set_physics_process_internal]).
 		</constant>
+		<constant name="NOTIFICATION_POST_ENTER_TREE" value="27">
+			Notification received when the node is ready, just before [constant NOTIFICATION_READY] is received. Unlike the latter, it's sent every time the node enters tree, instead of only once.
+		</constant>
 		<constant name="NOTIFICATION_WM_MOUSE_ENTER" value="1002">
 			Notification received from the OS when the mouse enters the game window.
 			Implemented on desktop and web platforms.

scene/main/node.cpp

@@ -2873,6 +2873,7 @@ void Node::_bind_methods() {
 	BIND_CONSTANT(NOTIFICATION_PATH_CHANGED);
 	BIND_CONSTANT(NOTIFICATION_INTERNAL_PROCESS);
 	BIND_CONSTANT(NOTIFICATION_INTERNAL_PHYSICS_PROCESS);
+	BIND_CONSTANT(NOTIFICATION_POST_ENTER_TREE);
 
 	BIND_CONSTANT(NOTIFICATION_WM_MOUSE_ENTER);
 	BIND_CONSTANT(NOTIFICATION_WM_MOUSE_EXIT);