Bug: iife should startsWith var instead of const evev if i set preset to es2015

[Jackie1210]

Rollup Version

2.77.0

Operating System (or Browser)

macOS

Node Version (if applicable)

16.13.0

Link To Reproduction

https://stackblitz.com/edit/rollup-template-83kwfj?file=rollup.config.js

Expected Behaviour

var lib = (function (exports) {
	'use strict';

	// run `node index.js` in the terminal

	const a = 'a';

	exports.a = a;

	Object.defineProperties(exports, { __esModule: { value: true }, [Symbol.toStringTag]: { value: 'Module' } });

	return exports;

})({});

Actual Behaviour

const lib = (function (exports) {
	'use strict';

	// run `node index.js` in the terminal

	const a = 'a';

	exports.a = a;

	Object.defineProperties(exports, { __esModule: { value: true }, [Symbol.toStringTag]: { value: 'Module' } });

	return exports;

})({});

[lukastaegert]

What is the bug you experience? When executed in a script scope, doesn't const still declare a global variable?

[Jackie1210]

@lukastaegert yep，you can check this.

vitejs/vite#9318

[lukastaegert]

Fix at #4588