Typescript does not recognize function Boolean() as a check for undefined

I followed the submission guidelines.

I prefer to check for a defined object using Boolean(object) rather than !!object, which I consider bad style. Typescript linter recognizes !! as a check for undefined but does not recognize Boolean() as a check for undefined.

I could not find a tsconfig or tslint configuration setting related to this behavior.

2.9.0-dev.20180511 (typescript@next)

"Boolean" "Boolean(" "function Boolean"

Code
This is not production code but a simple demonstration only to satisfy the expression tree.

function booleanTest() {
    let value: Array<object> | undefined = undefined;

    if (Date.now() > 1) {
        value = [{}];
    }

    if (Boolean(value)) {
        console.log(value.length);
    }
}

Expected behavior:
No Typescript linter errors

Actual behavior:
Typescript linter in VS Code displays an error "[ts] Object is possibly 'undefined'." with a red squiggly on the final reference to variable "value".

Playground Link:

Comienza con el ejemplo de TypeScript proporcionado e investiga la ruta de comprobación de tipos para el estrechamiento del flujo de control mediante Boolean(value), comparándola con la forma reconocida !!value. Se considera terminado cuando el ejemplo deja de informar de que value puede ser undefined, manteniendo al mismo tiempo el comportamiento correcto para otras llamadas a Boolean.