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

**What is the current behavior?**
In mobile Safari, DOM events originating from elements rendered through a Portal do **not** bubble (propagate) up the React component tree.

**If the current behavior is a bug, please provide the steps to reproduce....**
Please see the following JSFiddle: https://jsfiddle.net/zebulonj/wf7orwan/

In this JSFiddle, the expected behavior (seen in a desktop browser) is that clicking on the portal content (appearing as a modal, including backdrop) should toggle to the "On" or "Off" indicator rendered in the main content. However, in mobile Safari (iOS 11.1.1), the click events do not propagate.


**What is the expected behavior?**
Click events should propagate up the React component tree.

**Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?**
Affected: React 16.2
iOS 11.1.1

(updatePayload = updatePayload || []).push(propKey, nextProp);
    }
  }
  if (styleUpdates) {
    (updatePayload = updatePayload || []).push(STYLE, styleUpdates);
  }
  return updatePayload;
}
export function updateProperties(
  domElement: Element,
  updatePayload: Array<any>,
  tag: string,
  lastRawProps: Object,
  nextRawProps: Object,
): void {
  
  
  
  if (
    tag === 'input' &&
    nextRawProps.type === 'radio' &&
    nextRawProps.name != null
  ) {
    ReactDOMFiberInput.updateChecked(domElement, nextRawProps);
  }
  const wasCustomComponentTag = isCustomComponent(tag, lastRawProps);
  const isCustomComponentTag = isCustomComponent(tag, nextRawProps);