Add getDisplayList method to layer game object

src/gameobjects/layer/Layer.js

@@ -918,6 +918,38 @@ var Layer = new Class({
         return this;
     },
 
+    /**
+     * Returns a reference to the underlying display list _array_ that contains this Game Object,
+     * which will be either the Scene's Display List or the internal list belonging
+     * to its parent Container, if it has one.
+     * 
+     * If this Game Object is not on a display list or in a container, it will return `null`.
+     * 
+     * You should be very careful with this method, and understand that it returns a direct reference to the
+     * internal array used by the Display List. Mutating this array directly can cause all kinds of subtle
+     * and difficult to debug issues in your game.
+     *
+     * @method Phaser.GameObjects.Layer#getDisplayList
+     * @since 3.85.0
+     *
+     * @return {?Phaser.GameObjects.GameObject[]} The internal Display List array of Game Objects, or `null`.
+     */
+    getDisplayList: function ()
+    {
+        var list = null;
+
+        if (this.parentContainer)
+        {
+            list = this.parentContainer.list;
+        }
+        else if (this.displayList)
+        {
+            list = this.displayList.list;
+        }
+
+        return list;
+    },
+
     /**
      * Destroys this Layer removing it from the Display List and Update List and
      * severing all ties to parent resources.