go/ast: document that (*ast.File).Comments is sorted by position
This is the way that go/parser produces it and in every AST manipulation
that we do, we preserve such property. Also printer expects it is such
order.
Change-Id: I6a6a696424a679a2cf1f9bb7eb41bdd47523efa9
Reviewed-on: https://go-review.googlesource.com/c/go/+/704255
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>