It seems like those were intended to be public APIs (https://github.com/facebook/react/pull/10629) but they’re not published on npm because `lib` folder is not in the `"files"` whitelist.
/**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
'use strict';
var Circle = require('react-art/lib/Circle.art');
var React = require('react');
var ReactART = require('react-art');
var Group = ReactART.Group;
var Shape = ReactART.Shape;
var Surface = ReactART.Surface;
var Transform = ReactART.Transform;
var MOUSE_UP_DRAG = 0.978;
var MOUSE_DOWN_DRAG = 0.9;
var MAX_VEL = 11;
var CLICK_ACCEL = 3;
var BASE_VEL = 0.15;
/**
 * An animated SVG component.
 */
class VectorWidget extends React.Component {