Wrapped test nodes not accessible if within functional children

[jellison]

Bug

In the documentation, wrapped test nodes are direct children in the assertion:

const baseTemplate = assertion(() =>
    <div>
        <WrappedTestNode />
    </div>
);

If the wrapped test node is not a direct child - but instead used within a functional child - the node is not accessible via the Assertion API for modification.

For example, consider this WrappedTestNode that is a functional child of SomeOtherWidget:

const baseTemplate = assertion(() =>
    <div>
        <SomeOtherWidget>
            {
                content: () => <WrappedTestNode />
            }
        </SomeOtherWidget>
    </div>
);

Fixed assertions will function as expected, but any assertions that modify the WrappedTestNode - such as baseAssertion.setChildren(WrappedTestNode, () => 'blah') - will fail with the following message: Error: Unable to find node.

Expected

Functional children of widgets within an assertion template are executed in such a way that they are accessible via the Assertion API.

[maier49]

My fix for this only fixed the case where the function is a property on an object. Reopening since this is still broken for a functional child passed directly