Parentheses in type literals

[ahejlsberg]

This change adds support for parentheses in type literals. For example:

var a: (string | number)[];
var b: (() => string)[];
var b: (() => string) | (() => number);
var c: ((() => string) | (() => number))[];

There is a formal definition of the grammar in the updated language specification, but basically the grammar requires parentheses in the following cases:

• When function and constructor types are used in union types.
• When union, function, and constructor types are used in array types.

Similar to expressions, parentheses may be used for clarity in other contexts even if they aren't necessary.

[CyrusNajmabadi]

👍 Very nice. Looks clean and simple. I wish the CR for the spec update parts were easier to understand (but that's not under your control).