fix: support forwardRef with out of line argument

[motiz88]

Enables handlers that support forwardRef (defaultProps and Flow type handling) to work when the argument to forwardRef is a reference to a function defined outside of the forwardRef call:

import React from 'react';
const ComponentImpl = ({ foo = 'bar' }, ref) => <div ref={ref}>{foo}</div>;
React.forwardRef(ComponentImpl);

This is achieved by reusing resolveToValue.

Note that this does not fix the rebinding case, which I intend to tackle separately:

import React from 'react';
let ComponentImpl = ({ foo = 'bar' }, ref) => <div ref={ref}>{foo}</div>;
ComponentImpl = React.forwardRef(ComponentImpl); // resolveToValue resolves here :/

[danez]

Hi @motiz88, nice to see you again. Thanks for the PR. lgtm