This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

'of <p>.' +
          addendum,
      );
    });
    it('warns nicely for table rows', () => {
      spyOn(console, 'error');
      class Row extends React.Component {
        render() {
          return <tr>x</tr>;
        }
      }
      class Foo extends React.Component {
        render() {
          return <table><Row /> </table>;
        }
      }
      ReactTestUtils.renderIntoDocument(<Foo />);
      expectDev(console.error.calls.count()).toBe(3);
      var addendum1 = ReactDOMFeatureFlags.useFiber
        ? '\n    in tr (at **)' +
            '\n    in Row (at **)' +
            '\n    in table (at **)' +
            '\n    in Foo (at **)'
        : ' See Foo > table > Row > tr.';
      expectDev(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
        'Warning: validateDOMNesting(...): <tr> cannot appear as a child of ' +
          '<table>. Add a <tbody> to your code to match the DOM tree generated ' +
          'by the browser.' +
          addendum1,
      );