**Do you want to request a *feature* or report a *bug*?**

bug? Maybe.

**What is the current behavior?**

Using non-delegated handler for submit event.

**What is the expected behavior?**

After IE9, at least I know, submit event bubbled up.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**

16.2.0
if (
      isCustomComponentTag &&
      !didWarnShadyDOM &&
      (domElement: any).shadyRoot
    ) {
      warning(
        false,
        '%s is using shady DOM. Using shady DOM with React can ' +
          'cause things to break subtly.',
        getCurrentFiberOwnerNameInDevOrNull() || 'A component',
      );
      didWarnShadyDOM = true;
    }
  }
  
  let props: Object;
  switch (tag) {
    case 'iframe':