Fixed toJSON typos. See #6252.

src/materials/MeshNormalMaterial.js

@@ -45,7 +45,7 @@ THREE.MeshNormalMaterial.prototype.clone = function () {
 
 };
 
-THREE.MeshPhongMaterial.prototype.toJSON = function () {
+THREE.MeshNormalMaterial.prototype.toJSON = function () {
 
 	var data = THREE.Material.prototype.toJSON.call( this );
 

src/materials/PointCloudMaterial.js

@@ -65,7 +65,7 @@ THREE.PointCloudMaterial.prototype.clone = function () {
 
 };
 
-THREE.MeshDepthMaterial.prototype.toJSON = function () {
+THREE.PointCloudMaterial.prototype.toJSON = function () {
 
 	var data = THREE.Material.prototype.toJSON.call( this );