WebGL masking issue fixed

WebGL mask objects can now be nested within masked objects

examples/example 15 - Filters/indexAll.html

@@ -32,7 +32,7 @@
 	var gui = new dat.GUI({
     //height : 5 * 32 - 1,
     
-    width : 350
+    //width : 350
 	});
 	
 	var blurFilter = new PIXI.BlurFilter();