userAgentData is incomplete

[billy4479]

The navigator.userAgentData object lacks the platform key. According to MDN and the spec, it should be a string containing the underlying operating system, for example "Windows", "Linux" or "Android".

This "confuses" many websites that think can rely on userAgentData, because it's not undefined, but because it's incomplete it causes problems when the website tries to access userAgentData.platform. A website that shows this behavior (at the time writing) is web.snapchat.com.