SoftwareRenderer: Minor improvement.

examples/js/renderers/SoftwareRenderer.js

@@ -393,7 +393,7 @@ THREE.SoftwareRenderer = function ( parameters ) {
 		var id = material.id;
 		var shader = shaders[ id ];
 
-		if ( shaders[ id ] === undefined ) {
+		if ( shader === undefined ) {
 
 			if ( material instanceof THREE.MeshBasicMaterial ||
 				 material instanceof THREE.MeshLambertMaterial ||