JavaScript: Don't remove double negations

[greg-at-moderne]

What's changed?

Amending the SimplifyBooleanExpressionVisitor not to remove double negations from non-Java code. Unless the underlying type is already boolean.

What's your motivation?

In some languages, which include JavaScript and Groovy, the !! is an established technique of coercing values of different types into a truthy/falsey value. Therefore it's wrong to remove the !!. Example

function getDisplayName(user) {
    const name = user.name;       // could be undefined, null, or ""
    return !!name ? name : "Anonymous";
}