Set polyfill says it is [object Object] but should say [object Set]

Environment

Any - you can reproduce the issue using only file

https://github.com/facebook/react-native/blob/master/Libraries/vendor/core/Set.js

and any Javascript encironment.

EDIT: Just for the bot, it is completely irrelevant:

Environment:
OS: Windows 10
Node: 10.3.0
Yarn: Not Found
npm: 6.1.0
Watchman: Not Found
Xcode: N/A
Android Studio: Version 3.1.0.0 AI-173.4720617

Packages: (wanted => installed)
react: 16.3.1 => 16.3.1
react-native: 0.55.4 => 0.55.4

Description and Steps to Reproduce

Here is code that creates a simple Set object and then uses the spread operator to spread the Set's contents into a new array.

First, using an environment where the above file was executed/loaded (plus its own dependencies), and I also short-circuited the detection at the beginning that determines whether the polyfill is applied:

const s1 = new Set([1,2,3]);
console.log(Object.prototype.toString.call(s1));

Result:

[object Object]

Expected Behavior

Now for comparison a clean ES6+ environment without anything loaded, so we get a native Set implementation:

const s1 = new Set([1,2,3]);
console.log(Object.prototype.toString.call(s1));

Result:

[object Set]

Bắt đầu với Libraries/vendor/core/Set.js và tái hiện hành vi đã được báo cáo trong một môi trường JavaScript bằng cách sử dụng ví dụ Object.prototype.toString.call được cung cấp. So sánh kết quả của Set polyfill với kết quả của Set native; hoàn tất khi polyfill báo cáo [object Set] cho một thể hiện Set.