Install isTilemap prop used by physics system for fast type checking

Author: mikewesthad

src/gameobjects/tilemap/dynamiclayer/DynamicTilemapLayer.js

@@ -49,6 +49,13 @@ var DynamicTilemapLayer = new Class({
     {
         GameObject.call(this, scene, 'DynamicTilemapLayer');
 
+        /**
+         * Used internally by physics system to perform fast type checks.
+         * @property {boolean} isTilemap
+         * @readonly
+         */
+        this.isTilemap = true;
+
         /**
          * The Tilemap that this layer is a part of.
          * @property {Tilemap} map

src/gameobjects/tilemap/staticlayer/StaticTilemapLayer.js

@@ -49,6 +49,13 @@ var StaticTilemapLayer = new Class({
     {
         GameObject.call(this, scene, 'StaticTilemapLayer');
 
+        /**
+         * Used internally by physics system to perform fast type checks.
+         * @property {boolean} isTilemap
+         * @readonly
+         */
+        this.isTilemap = true;
+
         /**
          * The Tilemap that this layer is a part of.
          * @property {Tilemap} map