Object3D: Replaced some vars with let/const.

src/core/Object3D.js

@@ -7,23 +7,23 @@ import { Layers } from './Layers.js';
 import { Matrix3 } from '../math/Matrix3.js';
 import { MathUtils } from '../math/MathUtils.js';
 
-var _object3DId = 0;
+let _object3DId = 0;
 
-var _v1 = new Vector3();
-var _q1 = new Quaternion();
-var _m1 = new Matrix4();
-var _target = new Vector3();
+const _v1 = new Vector3();
+const _q1 = new Quaternion();
+const _m1 = new Matrix4();
+const _target = new Vector3();
 
-var _position = new Vector3();
-var _scale = new Vector3();
-var _quaternion = new Quaternion();
+const _position = new Vector3();
+const _scale = new Vector3();
+const _quaternion = new Quaternion();
 
-var _xAxis = new Vector3( 1, 0, 0 );
-var _yAxis = new Vector3( 0, 1, 0 );
-var _zAxis = new Vector3( 0, 0, 1 );
+const _xAxis = new Vector3( 1, 0, 0 );
+const _yAxis = new Vector3( 0, 1, 0 );
+const _zAxis = new Vector3( 0, 0, 1 );
 
-var _addedEvent = { type: 'added' };
-var _removedEvent = { type: 'removed' };
+const _addedEvent = { type: 'added' };
+const _removedEvent = { type: 'removed' };
 
 /**
  * @author mrdoob / http://mrdoob.com/