UnaryExpression doesn't parenthesize correctly

[NotWearingPants]

For some reason this is only a problem with arrow functions, and none of the other NEEDS_PARENTHESES nodes.

Using the online demo:

---

!(() => {});

turns into

!() => {};

which is a syntax error.

---

typeof (() => {});

turns into

typeof () => {};

which is a syntax error.