XMLHttpRequest corrupts headers named after Object prototype properties

Description

React Native XMLHttpRequest stores request headers and normalized response headers in ordinary objects. Valid header names that collide with Object.prototype are therefore corrupted or hidden: repeated Constructor values begin with inherited function text, __proto__ cannot be stored normally, and an absent toString response header is returned as an inherited function instead of null.

Expected behavior

All valid case-insensitive header names should be stored, combined, and retrieved as their own values without interacting with JavaScript object prototypes.

React Native Version

0.87.1 and current main

Affected Platforms

JavaScript networking - All

从 React Native 的 XMLHttpRequest 实现开始，检查请求头和规范化响应头是如何存储和获取的。查找或添加针对 Constructor、proto 和缺失的 toString 请求头的专门测试；完成标准是，有效的不区分大小写的名称能够保留各自的值，且不会与 Object.prototype 发生交互。