Bug 282025 – REGRESSION: "tabs" field missing from windows.create returned windows.Window

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit Extensions

The `tabs` field missing from windows.create returned windows.Window, where the `tabs` field was supposed to be available according to MDN:

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/windows/create#return_value
>This Window object will always have its tabs property set, unlike the Window objects returned from windows.get() and similar APIs, which only contain tabs if the populate option is passed.

and it used to be available prior to Safari 18.

# Reproduce

manifest.json

```json
{
  "manifest_version": 2,
  "name": "example",
  "version": "0.0.0",
  "permissions": ["<all_urls>"],
  "background": {
    "page": "background.html",
    "persistent": true
  }
}
```

background.html

```html
<script type="module" crossorigin src="./background.js"></script>
```

background.js

```js
console.log(await browser.windows.create({ url: 'https://example.com', type: 'popup' }))
```

# Expected Result:

Safari 17.6

```json
{
  "alwaysOnTop": false,
  "focused": true,
  "height": 809,
  "id": 9,
  "incognito": false,
  "left": 184,
  "state": "normal",
  "tabs": [
    {
      "active": true,
      "audible": false,
      "height": 809,
      "highlighted": true,
      "id": 34,
      "incognito": false,
      "index": 0,
      "isArticle": false,
      "isInReaderMode": false,
      "mutedInfo": { "muted": false },
      "pendingUrl": "https://example.com/",
      "pinned": false,
      "status": "loading",
      "url": "https://example.com/",
      "width": 1010,
      "windowId": 9
    }
  ],
  "top": 25,
  "type": "popup",
  "width": 1010
}
```

# Actual Result:

Safari 18.0.1

```json
{
  "alwaysOnTop": false,
  "focused": true,
  "height": 1415,
  "id": 320718,
  "incognito": false,
  "left": 244,
  "state": "normal",
  "top": 25,
  "type": "popup",
  "width": 2316
}
```

[Radar WebKit Bug Importer]

<rdar://problem/138529797>

[Timothy Hatcher]

Pull request: https://github.com/WebKit/WebKit/pull/39047

[EWS]

Committed 288949@main (8e0fc5af568b): <https://commits.webkit.org/288949@main>

Reviewed commits have been landed. Closing PR #39047 and removing active labels.