Reflector Lighting Bug

HTML

<script src="https://rawgit.com/mrdoob/three.js/r88/build/three.js"></script>
<script src="https://rawgit.com/mrdoob/three.js/r88/examples/js/controls/OrbitControls.js"></script>
<script src="https://rawgit.com/mrdoob/three.js/r88/examples/js/objects/Reflector.js"></script>

JavaScript

var camera, scene, renderer, controls;

init();
render();

function init() {

  scene = new THREE.Scene();
  var aspectRatio = window.innerWidth / window.innerHeight;
  camera = new THREE.PerspectiveCamera(75, aspectRatio, 1, 1000);
  camera.position.set(-3, 3, -3);
  scene.add(camera);
  controls = new THREE.OrbitControls(camera);  

  var mirror = new THREE.Reflector(1, 1);
  mirror.receiveShadow = true;
  mirror.castShadow = true;
  mirror.position.z = -1;
  mirror.rotation.y = Math.PI;

  renderer = new THREE.WebGLRenderer({ antialias: true });
  renderer.setSize(window.innerWidth, window.innerHeight);
  renderer.shadowMap.enabled = true;
 
 // --------------------------------------------------------
  scene.add(mirror);
  renderer.render(scene, camera);
  createMirrorTest();
  mirror.material.needsUpdate = true;
 // --------------------------------------------------------

  document.body.appendChild(renderer.domElement);
}

function createMirrorTest()
{
  var light = new THREE.PointLight(0xF0F0F0, 1, 100000);
  light.position.set(1, 1, 1);
  light.castShadow = true;
  scene.add(light);

  var wallGeometry = new THREE.PlaneGeometry(6, 3);
  var floorGeometry = new THREE.BoxGeometry(6, 0.1, 6);
  var material1 = new THREE.MeshStandardMaterial({ color: 0xFFFF00 });
  var material2 = new THREE.MeshStandardMaterial({ color: 0x00FFFF });
  var material3 = new THREE.MeshStandardMaterial({ color: 0xFF00FF });
  var material4 = new THREE.MeshStandardMaterial({ color: 0xFFFFFF });
    
  var wall1 = new THREE.Mesh(wallGeometry, material1);
  wall1.receiveShadow = true;
  wall1.castShadow = true;
  wall1.position.z = -3;
  wall1.position.y = 1;
  scene.add(wall1);
  
  var wall2 = new THREE.Mesh(wallGeometry, material2);
  wall2.receiveShadow = true;
  wall2.castShadow = true;
  wall2.rotation.y = -Math.PI / 2;
  wall2.position.x = 3;
  wall2.position.y = 1;
  scene.add(wall2);
  
  var wall3 = new THREE.Mesh(wallGeometry, material3);
  wall3.receiveShadow = true;
 ...