Map is not cloned when passed as the root object

[laurence-myers]

Reproducible test scenario (using Mocha):

const deepClone = require('fast-deepclone');
const assert = require('assert');

describe(`fast-deepclone`, function () {
    it(`can deep copy a map`, function () {
        const map = new Map();
        map.set('key', 'value');

        const copiedMap = deepClone(map, true);
        assert.notStrictEqual(map, copiedMap, "Variables holding Maps should not reference the same object in memory");
        assert.strictEqual(map.size, copiedMap.size, "The cloned Map should have the same size as the original Map");
    });
});

This test will fail at the assertion "Variables holding Maps should not reference the same object in memory"