See the original report in https://github.com/facebook/react/issues/10772#issuecomment-333242375.

The problem is that SVG is case sensitive, and so naïvely setting `tabIndex` and relying on insensitivity won't work with it.

The good news is it seems like `tabindex` is the only valid [SVG attribute](https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute) with this problem. We just missed it because it applies both to HTML and SVG.

I think the fix is to add it back to the 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.
 *
 * @emails react-core
 */
'use strict';
let ExecutionEnvironment;
let PropTypes;
let React;
let ReactDOM;
let ReactDOMServer;
let ReactTestUtils;
const stream = require('stream');
const TEXT_NODE_TYPE = 3;
function asyncReactDOMRender(reactElement, domElement, forceHydrate) {
  return new Promise(resolve => {
    if (forceHydrate) {
      ReactDOM.hydrate(reactElement, domElement);
    } else {
      ReactDOM.render(reactElement, domElement);
    }
    
    
    resolve();
  });
}
async function expectErrors(fn, count) {