src/utils/isReference.js/isReference
export default function isReference ( node, parent ) {
	if ( node.type === 'MemberExpression' ) {
		return !node.computed && isReference( node.object, node );
	}

	if ( node.type === 'Identifier' ) {
		// the only time we could have an identifier node without a parent is
		// if it's the entire body of a function without a block statement –
		// i.e. an arrow function expression like `a => a`
		if ( !parent ) return true;

		// TODO is this right?
		if ( parent.type === 'MemberExpression' || parent.type === 'MethodDefinition' ) {
			return parent.computed || node === parent.object;
		}

		// disregard the `bar` in `{ bar: foo }`, but keep it in `{ [bar]: foo }`
		if ( parent.type === 'Property' ) return parent.computed || node === parent.value;

		// disregard the `bar` in `class Foo { bar () {...} }`
		if ( parent.type === 'MethodDefinition' ) return false;

		// disregard the `bar` in `export { foo as bar }`
		if ( parent.type === 'ExportSpecifier' && node !== parent.local ) return;

		return true;
	}
}