Use @param tags in function assignment

[billti]

Using the Salsa work with @param tags works fine for function declarations, but not for assignments of function expressions. This is particularly a problem in the CommonJS case. For example with the module below, sub correctly shows the params as of type number, whereas add shows them as type any.

/**
 * @param {number} a The number to subtract from
 * @param {number} b The number to subtract
 */
function sub(a, b) {
    return a - b;
}

exports.sub = sub;

/**
 * @param {number} a - First term
 * @param {number} b - Second term
 */
exports.add = function(a, b) {
    return a + b; 
}

The JsDoc tags should apply to the resulting value of the expression.