Fixed material grass example.

@gero: seems like previously WebGLRenderer will reverse() the transparent objects regardless of the sortObjects boolean. I think the new behaviour is right. But we should we aware that the behaviour changed here.

examples/webgl_materials_grass.html

@@ -55,6 +55,8 @@
 
 				}
 
+				scene.children.reverse();
+
 				renderer = new THREE.WebGLRenderer();
 				renderer.sortObjects = false;
 				renderer.setClearColor( 0x003300 );