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: