It seems like react-is v16.6 no longer is compatible with React v16.3 - v16.5, in that React v16.3 - v16.5 will use `Symbol(react.async_mode)`, but `react-is`'s `AsyncMode` export will instead be `Symbol(react.concurrent_mode)`.

It seems like the async mode symbol needs to remain the same in react-is 16.6+, and the `isAsyncMode` function would need to check *both* the AsyncMode and ConcurrentMode symbols.
return typeOf(object) === REACT_CONTEXT_TYPE;
}
export function isContextProvider(object: any) {
  return typeOf(object) === REACT_PROVIDER_TYPE;
}
export function isElement(object: any) {
  return (
    typeof object === 'object' &&
    object !== null &&
    object.$$typeof === REACT_ELEMENT_TYPE
  );
}
export function isForwardRef(object: any) {
  return typeOf(object) === REACT_FORWARD_REF_TYPE;
}
export function isFragment(object: any) {
  return typeOf(object) === REACT_FRAGMENT_TYPE;
}
export function isProfiler(object: any) {
  return typeOf(object) === REACT_PROFILER_TYPE;
}
export function isPortal(object: any) {
  return typeOf(object) === REACT_PORTAL_TYPE;
}
export function isStrictMode(object: any) {
  return typeOf(object) === REACT_STRICT_MODE_TYPE;
}