Fixed shadows in cars demo.

Bah, this one was tricky. World positions are not updated for objects that are not part of the scene graph so spotlight target was just hanging in limbo.

examples/webgl_materials_cubemap_dynamic.html

@@ -178,6 +178,7 @@
 				spotLight.shadowMapHeight = SHADOW_MAP_HEIGHT;
 
 				scene.add( spotLight );
+				scene.add( spotLight.target );
 
 				directionalLight2 = new THREE.PointLight( 0xff9900, 0.25 );
 				directionalLight2.position.set( 0.5, -1, 0.5 );