**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

suppressHydrationWarning?: boolean,
  dangerouslySetInnerHTML?: mixed,
};
export type Container = Element | Document;
export type Instance = Element;
export type TextInstance = Text;
export type HydratableInstance = Element | Text;
export type PublicInstance = Element | Text;
type HostContextDev = {
  namespace: string,
  ancestorInfo: mixed,
};
type HostContextProd = string;
export type HostContext = HostContextDev | HostContextProd;
export type UpdatePayload = Array<mixed>;
export type ChildSet = void; 
export type TimeoutHandle = TimeoutID;
export type NoTimeout = -1;
export {
  now,
  scheduleWork as scheduleDeferredCallback,
  cancelScheduledWork as cancelDeferredCallback,
} from 'shared/ReactScheduler';
let SUPPRESS_HYDRATION_WARNING;
if (__DEV__) {
  SUPPRESS_HYDRATION_WARNING = 'suppressHydrationWarning';
}
let eventsEnabled: ?boolean = null;
let selectionInformation: ?mixed = null;
function shouldAutoFocusHostComponent(type: string, props: Props): boolean {