why inside If statement is exempt

[JiaYifan]

The question is, the code in If statement is exempt from browser compatibility check. It seems unreasonable.

[bschlenk]

I think it's meant to allow checking for the existence of a thing before using it, like

if (window.fetch) {
  fetch()
}

But it's too broad because it also means it doesn't catch

if (true) {
  fetch()
}