**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

);
  };
  warnForPropDifference = function(
    propName: string,
    serverValue: mixed,
    clientValue: mixed,
  ) {
    if (didWarnInvalidHydration) {
      return;
    }
    const normalizedClientValue = normalizeMarkupForTextOrAttribute(
      clientValue,
    );
    const normalizedServerValue = normalizeMarkupForTextOrAttribute(
      serverValue,
    );
    if (normalizedServerValue === normalizedClientValue) {
      return;
    }
    didWarnInvalidHydration = true;
    warningWithoutStack(
      false,
      'Prop `%s` did not match. Server: %s Client: %s',
      propName,
      JSON.stringify(normalizedServerValue),
      JSON.stringify(normalizedClientValue),
    );
  };
  warnForExtraAttributes = function(attributeNames: Set<string>) {
    if (didWarnInvalidHydration) {