**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

switch (type) {
    case 'button':
    case 'input':
    case 'select':
    case 'textarea':
      return !!props.autoFocus;
  }
  return false;
}
export * from 'shared/HostConfigWithNoPersistence';
export function getRootHostContext(
  rootContainerInstance: Container,
): HostContext {
  let type;
  let namespace;
  const nodeType = rootContainerInstance.nodeType;
  switch (nodeType) {
    case DOCUMENT_NODE:
    case DOCUMENT_FRAGMENT_NODE: {
      type = nodeType === DOCUMENT_NODE ? '#document' : '#fragment';
      let root = (rootContainerInstance: any).documentElement;
      namespace = root ? root.namespaceURI : getChildNamespace(null, '');
      break;
    }
    default: {
      const container: any =
        nodeType === COMMENT_NODE
          ? rootContainerInstance.parentNode
          : rootContainerInstance;
      const ownNamespace = container.namespaceURI || null;