ZeroNet still seeds a site when inner iframe was not loaded.

```html

function get(url) {
var r = new XMLHttpRequest();
r.onload = function() {
console.log(r.responseText);
};
r.open("GET", url);
r.send();
}

get("/13Lo9wpxbogHdaTQ9rGZruu9MJZnigzU3B/");
get("/1CiDoBP8RiWziqiBGEd8tQMy66A6fmnw2V/big/sample-loader/files/list.json");
console.log("Request sent.");

```

```
Request sent.
! Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://127.0.0.1:43110/13Lo9wpxbogHdaTQ9rGZruu9MJZnigzU3B/. (Reason: CORS header ‘Access-Control-Allow-Origin’ missing).
```

Site **still seeded** and appeared.

从 issue 中的 HTML/JavaScript XMLHttpRequest 复现开始，跟踪 ZeroNet 如何处理失败的内部请求。完成的标准是：当内部 iframe 或请求未加载时，站点不会继续 seeding，也不会出现，并且提供的复现不再显示所报告的行为。

由索引模型根据 Issue 内容生成。