code: function RectAreaLightHelper( light, color ) {
  
  	this.type = 'RectAreaLightHelper';
  
  	this.light = light;
  
  	this.color = color; // optional hardwired color for the helper
  
  	var positions = [ 1, 1, 0, - 1, 1, 0, - 1, - 1, 0, 1, - 1, 0, 1, 1, 0 ];
  
  	var geometry = new BufferGeometry();
  	geometry.addAttribute( 'position', new Float32BufferAttribute( positions, 3 ) );
  	geometry.computeBoundingSphere();
  
  	var material = new LineBasicMaterial( { fog: false } );
  
  	Line.call( this, geometry, material );
  
  	//
  
  	var positions2 = [ 1, 1, 0, - 1, 1, 0, - 1, - 1, 0, 1, 1, 0, - 1, - 1, 0, 1, - 1, 0 ];
  
  	var geometry2 = new BufferGeometry();
  	geometry2.addAttribute( 'position', new Float32BufferAttribute( positions2, 3 ) );
  	geometry2.computeBoundingSphere();
  
  	this.add( new Mesh( geometry2, new MeshBasicMaterial( { side: THREE.BackSide, fog: false } ) ) );
  
  	this.update();
  
  }
docs: @author abelnation / http://github.com/abelnation
  @author Mugen87 / http://github.com/Mugen87
  @author WestLangley / http://github.com/WestLangley
  
  This helper must be added as a child of the light