See comment here: https://github.com/facebook/react/pull/11457#discussion_r148954193.

Although it seems very unlikely that someone would pass a one-character prop, the price (at least in versions of V8 in Chrome right now) is reported to be about 10x.

So we should check `.length` first and then do the comparison.

**Please comment if you want to take this issue.**
**If somebody already commented, please let them finish it.**
/**
 * 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.
 */
import invariant from 'fbjs/lib/invariant';
var RESERVED_PROPS = {
  children: true,
  dangerouslySetInnerHTML: true,
  defaultValue: true,
  defaultChecked: true,
  innerHTML: true,
  suppressContentEditableWarning: true,
  suppressHydrationWarning: true,
  style: true,
};
function checkMask(value, bitmask) {