valFn = function (v) {
            if (v == null) return true;
            if (typeof v === "string") {
                try {
                    return !isNaN(Date.parse(v));
                    // old code
                    // return __isDate(new Date(v));
                } catch (e) {
                    return false;
                }
            } else {
                return __isDate(v);
            }
        }
Returns a standard date data type Validator.
    @example
        // Assume em1 is a preexisting EntityManager.
        var orderType = em1.metadataStore.getEntityType("Order");
        var orderDateProperty - orderType.getProperty("OrderDate");
        // Validates that the value of the OrderDate property on Order is a date
        // Probably not a very good validation to place on the Freight property.
        orderDateProperty.validators.push(Validator.date());
    @method date
    @static
    @return {Validator} A new Validator