Shorthand properties like { x } are currently expanded to { x: x } when using any module format other than ES6. This PR changes this to apply to an ES6+ script target instead.

The special cases considered now also includes whether the current module format has direct or indirect access to imported identifiers. The ES6 and System formats for example have direct access, all others have indirect access. This means that the shorthand properties must be expanded, even for ES6+ script targets if the identifier is indirectly imported.

For example, the object expression in code below can be preserved as is when targeting ES6+ with an ES6 or System module format.

Update: After discovering that TypeScript doesn't generate direct identifier accesses for the System module format, the changes now only affects ES6 modules.

import { foo } from './foo';
export const bar = { foo };

// es6
import { foo } from './foo';
export const bar = { foo };

but is expanded for all other formats.

// system
System.register(['./foo'], function(exports_1, context_1) {
    "use strict";
    var __moduleName = context_1 && context_1.id;
    var foo_1;
    var bar;
    return {
        setters:[
            function (foo_1_1) {
                foo_1 = foo_1_1;
            }],
        execute: function() {
            exports_1("bar", bar = { foo: foo_1.foo });
        }
    }
});

// cjs
"use strict";
const foo_1 = require('./foo');
exports.bar = { foo: foo_1.foo };

// amd
define(["require", "exports", './foo'], function (require, exports, foo_1) {
    "use strict";
    exports.bar = { foo: foo_1.foo };
});

Fixes #7434