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.

var setTextContent = require('setTextContent');
var inputValueTracking = require('inputValueTracking');
var warning = require('fbjs/lib/warning');
if (__DEV__) {
  var ReactDOMInvalidARIAHook = require('ReactDOMInvalidARIAHook');
  var ReactDOMNullInputValuePropHook = require('ReactDOMNullInputValuePropHook');
  var ReactDOMUnknownPropertyHook = require('ReactDOMUnknownPropertyHook');
  var {validateProperties: validateARIAProperties} = ReactDOMInvalidARIAHook;
  var {
    validateProperties: validateInputPropertes,
  } = ReactDOMNullInputValuePropHook;
  var {
    validateProperties: validateUnknownPropertes,
  } = ReactDOMUnknownPropertyHook;
}
var didWarnShadyDOM = false;
var listenTo = ReactBrowserEventEmitter.listenTo;
var registrationNameModules = EventPluginRegistry.registrationNameModules;
var DANGEROUSLY_SET_INNER_HTML = 'dangerouslySetInnerHTML';
var SUPPRESS_CONTENT_EDITABLE_WARNING = 'suppressContentEditableWarning';
var CHILDREN = 'children';
var STYLE = 'style';
var HTML = '__html';
var {
  html: HTML_NAMESPACE,
  svg: SVG_NAMESPACE,
  mathml: MATH_NAMESPACE,
} = DOMNamespaces;
var DOC_FRAGMENT_TYPE = 11;
function getDeclarationErrorAddendum() {