Added stencil support to frame

Playground/frame.js

@@ -44,7 +44,7 @@
             }
 
             var canvas = document.getElementById("renderCanvas");
-            engine = new BABYLON.Engine(canvas, true);
+            engine = new BABYLON.Engine(canvas, true, {stencil: true});
             engine.renderEvenInBackground = false;
             BABYLON.Camera.ForceAttachControlToAlwaysPreventDefault = true;