Passing a `MouseEvent` as the arg to `simulate('click', ...)` doesn't maintain properties

# Current behavior

When using `wrapper.simulate('click')` the Synthetic event does not contain default `MouseEvent` properties, like `button`. This is okay since simulate is a generic method.

However, I created a `MouseEvent` object, and attempt to pass this as the second argument to `simulate`, to ensure the expected `MouseEvent` properties are populated, but none of them are.

Passing a simple object with only the `button`, and `buttons` properties, the props are correctly passed through to the onClick handler.

Doesn't work:
```ts
it.each(testTabs)(`Should render each tab when clicked %o`, tab => {
const mouseEvent: MouseEvent = new MouseEvent("click", {
button: 0,
buttons: 1
});
wrapper.find(`a[href="${baseRoute}${tab.relativePath}"]`).simulate("click", mouseEvent);

expect(wrapper.contains(`${tab.title} Content`)).toBeTruthy();
});
```

Works:
```ts
it.each(testTabs)(`Should render each tab when clicked %o`, tab => {
wrapper.find(`a[href="${baseRoute}${tab.relativePath}"]`).simulate("click", { button: 0, buttons: 1 });

expect(wrapper.contains(`${tab.title} Content`)).toBeTruthy();
});
```

### Expected behavior

If I pass a real `MouseEvent` object as arg to the `simulate('click', ...)` that properties from the `MouseEvent` should be passed through to the invoked handler.

### Your environment

Win 10 18363.778, Webpack 4.42.1, Jest 25.4.0, using jsDOM.

#### API

- [ ] shallow
- [X] mount
- [ ] render

#### Version

| library | version
| ------------------- | -------
| enzyme | 3.11.0
| react | 16.13.1
| react-dom | 16.13.1
| react-test-renderer | 16.13.1
| adapter (below) | 1.15.2

#### Adapter

- [X] enzyme-adapter-react-16
- [ ] enzyme-adapter-react-16.3
- [ ] enzyme-adapter-react-16.2
- [ ] enzyme-adapter-react-16.1
- [ ] enzyme-adapter-react-15
- [ ] enzyme-adapter-react-15.4
- [ ] enzyme-adapter-react-14
- [ ] enzyme-adapter-react-13
- [ ] enzyme-adapter-react-helper
- [ ] others ( )