function extractName( node ) {
	var prop;
	if ( node.callee.type === 'MemberExpression' ) {
		prop = node.callee.property;
		if ( prop.type === 'Literal' && isString( prop.value ) ) {
			return prop.value;
		}
		if ( prop.type === 'Identifier' && !node.callee.computed ) {
			return prop.name;
		}
		return null;
	}
	return node.callee.name;
}
Extract callee name from call expression.

@private
@param {ASTNode} node - CallExpression node
@returns {(string|null)} callee name