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.

keygen: true,
  link: true,
  meta: true,
  param: true,
  source: true,
  track: true,
  wbr: true,
  
};
var newlineEatingTags = {
  listing: true,
  pre: true,
  textarea: true,
};
var voidElementTags = Object.assign(
  {
    menuitem: true,
  },
  omittedCloseTags,
);
var VALID_TAG_REGEX = /^[a-zA-Z][a-zA-Z:_\.\-\d]*$/; 
var validatedTagCache = {};
var hasOwnProperty = {}.hasOwnProperty;
function validateDangerousTag(tag) {
  if (!hasOwnProperty.call(validatedTagCache, tag)) {
    invariant(VALID_TAG_REGEX.test(tag), 'Invalid tag: %s', tag);
    validatedTagCache[tag] = true;
  }
}
function isCustomComponent(tagName, props) {