And change clients of parser and AstBuilder (within the SDK) to use
it.
Long term, it would be better to store the FeatureSet object directly
in the AstBuilder and remove the existing flags `enableNonNullable`,
`enableSpreadCollections`, `enableControlFlowCollections`, and
`enableControlFlowCollections`. However there are analyzer clients
that currently use these flags. So for now, we simply plumb in the
FeatureSet as a new way of setting AstBuilder flags. Once we've
updated clients to use FeatureSet, we'll publish a breaking version of
the analyzer that removes the old flag API.
Change-Id: I6d37177c40b1a1216956e95f473252aa218d10b8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100000
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Dan Rubel <danrubel@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
danrubel