Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a bug report that matches the one I want to file, without success.

Electron Version

33.0.0-nightly.20240808

What operating system(s) are you using?

macOS

Operating System Version

macOS 14.6.1

What arch are you using?

arm64 (including Apple Silicon)

Last Known Working Electron version

No response

Reproduction steps

1. Start following app:

const {app, BrowserWindow, BrowserView} = require('electron')

app.once('ready', async () => {
  window = new BrowserWindow({
    width: 800,
    height: 600,
    show: true
  })

  window.webContents.setWindowOpenHandler(({ url }) => {
    console.log(`open window: ${url}`);
    return {
      action: 'allow',
      createWindow: (options) => {
        const child = new BrowserWindow({
            webContents: options?.webContents,
            webPreferences: options?.webPreferences
        });

        return child.webContents;
      }
    }
  });

  await window.webContents.loadURL('https://www.example.com');
});

2. Open devtools window
3. Execute: let win = window.open('about:blank')

Expected Behavior

win.document can be accessed

Actual Behavior

win.document can't be accessed: it fails with error:

Uncaught SecurityError: Failed to read a named property 'document' from 'Window': Blocked a frame with origin "https://www.example.com" from accessing a cross-origin frame.

Testcase Gist URL

No response

Additional Information

win.document can be accessed when child window creation is not overriden by WebContents::setWindowOpenHandler.

No response