[Web API type definition issue] Element.requestFullscreen should be optional #2211

Summary

typeof document.documentElement.requestFullscreen is undefined in iOS Safari

Expected vs. Actual Behavior

typeof document.documentElement.requestFullscreen

Expected: not defined in iOS 26.0.1 Safari (and probably in the webview)
Actual: always a function

Playground Link

No response

Browser Support

• This API is supported in at least two major browser engines (not two Chromium-based browsers).

Have Tried The Latest Releases

• This issue applies to the latest release of TypeScript.
• This issue applies to the latest release of @types/web.

Additional Context

Suggested change will enforce optional chaining for safer runtime code.

document.documentElement.requestFullscreen?.()