valFn = function (v, ctx) {
            if (v == null) return true;
            if (typeof v === "string" && ctx && ctx.allowString) {
                v = parseInt(v, 10);
            }
            return (typeof v === "number") && (!isNaN(v)) && Math.floor(v) === v;
        }
Returns a standard large integer data type - 64 bit - Validator.
    @example
        // Assume em1 is a preexisting EntityManager.
        var orderType = em1.metadataStore.getEntityType("Order");
        var freightProperty - orderType.getProperty("Freight");
        // Validates that the value of the Freight property on Order is within the range of a 64 bit integer.
        freightProperty.validators.push(Validator.int64());
    @method int64
    @static
    @return {Validator} A new Validator