Clean up MeshFaceMaterial clone code.

src/materials/MeshFaceMaterial.js

@@ -9,9 +9,7 @@ THREE.MeshFaceMaterial = function ( materials ) {
 };
 
 THREE.MeshFaceMaterial.prototype.clone = function () {
-	
-	var material = new THREE.MeshFaceMaterial();
-	material.materials = this.materials.slice(0);
-	return material;
+
+	return new THREE.MeshFaceMaterial( this.materials.slice( 0 ) );
 
 };