Document some of the API stability guarantees that are required for the command line
API of the frontend_server binary. This will allow package:test and the webdev CLI to
begin using the frontend_server
Change-Id: I4bf05757c527e491b1059489b5dda53dfda876a4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/174840
Reviewed-by: Alexander Aprelev <aam@google.com>
Commit-Queue: Jonah Williams <jonahwilliams@google.com>
jonahwilliams