Adapter React 16 does not support new Portal node types

[flakeparadigm]

Attempting to mount a component that renders a new Portal component type throws an error because then React 16 adapter does not know how to handle the node tag (4).

Thrown error: Error: Enzyme Internal Error: unknown node with tag 4

Enzyme method throwing the error: https://github.com/airbnb/enzyme/blob/master/packages/enzyme-adapter-react-16/src/ReactSixteenAdapter.js#L59

The full list of React node "tags", of which there are many unimplemented in this method, can be found here: https://github.com/facebook/react/blob/master/src/shared/ReactTypeOfWork.js

Example code to reproduce this error:

class TestComponent extends React.Component {
    constructor(props) {
        super(props);
        this.el = document.createElement('div');
    }

    render() {
        return ReactDOM.createPortal(
            <div>Hello World</div>,
            this.el
        );
    }
}

enzyme.mount(<TestComponent />);

[ljharb]

Duplicate of #1150.