Allow type casts around shorthand property names

[JoshuaKGoldberg]

Is there any reason shorthand property names ({ a }, etc.) don't allow type casting around the names? It would be a mildly useful feature.

Code

The following object literals are all intended to compile to { foo: foo }:

function take(arg: { foo: string }) { }

let foo: string;

// Allowed
take({ foo });
take({ foo: foo });
take({ foo: foo as string });
take({ foo: <string>foo });

// Syntax errors
take({ <string>foo });
take({ foo as string });

Expected behavior:
These should all compile to the same thing.

Actual behavior:
The lines with type casting in the names are syntax errors.

[JoshuaKGoldberg]

I've found variants of catch(error) come up once in a while and get flagged by TSLint for unsafe any usage without type casts:

try {
    return {
        data: riskyOperation(),
        succeeded: true,
    };
} catch (error) {
    return {
        error: error as Error,
        succeeded: false
    };
}

[RyanCavanaugh]

Somewhat wurprised at the lack of feedback here, but in practice this isn't a huge annoyance for me when I encounter it so maybe that makes sense. I think we want to stay well-clear of this syntactic space to keep room for future TC39.